Two years ago, Zhen You Mo received a notice from his employer informing him that his job as an assistant at Quinzani’s Bakery was ending because developers had purchased the space, conveniently located steps from Mo’s Harrison Avenue home.

Now, ongoing development in the South End neighborhood is threatening his home.

“It was tough when I found out I was going to lose my job, and now I’m about to lose my home, and it’s difficult,’’ Mo, 50, said in Chinese through a translator. “Landlords are fixing up apartments to rent out to people who can afford more, but we don’t have a place to go and it also feels like there isn’t much we can do.’’

It’s a familiar story in the South End and other rapidly changing city neighborhoods like Chinatown and East Boston: Investors eager for new properties to develop are pushing up prices, tempting owners to sell small residential and commercial spaces where longtime residents live and work.

In Mo’s case, a local investor has offered to pay $2 million for the four-story brick row house where he rents a small two-bedroom first floor apartment with his wife, 13-year-old daughter, and 8-year-old son. About 14 people live in the building, which could be converted into a condo complex.

The family trust that has owned the property for 30 years has signed a purchase and sale agreement and in May gave tenants 30 days notice, telling them they would have to move out by the end of June. But the residents, with the help of an advocacy group, are fighting to stay put. They have what they hope is a powerful ally in Lam Chung Chu, the fourth floor tenant and building manager who also is one of the five family trustees. Chu, who has lived in the building for 30 years and owns 25 percent of the property, doesn’t want to sell. But he’s outnumbered — two of Chu’s brothers, who handle the property’s business matters, own 50 percent of the property, while his two sisters own the other 25 percent. Lam Chung Chu said he’s the only one who opposes the sale. Attorneys representing the trust did not return messages seeking comment.

Karen Chen, codirector of the Chinese Progressive Association, which is assisting the tenants, said property records show the trust, formed in 1989, was set to expire 20 years after it was created, meaning that it may have been defunct since 2009 — an argument they hope a Boston Housing Court judge will agree nullifies the evictions and, ultimately, the sale of the building.

Chen said this is just one of many eviction cases the association is dealing with, not merely to stop landlords from selling, but to pressure city officials into coming up with “some sort of policy that limits land speculation, but also stabilizes people’s rents.’’

Through a translator, Lam Chung Chu said all the tenants at 410-412 Harrison Ave. pay below-market rents, allowing them to afford to live and work in the area. As the building manager, Chu pays just $550 a month for a three-bedroom unit he shares with his wife. It’s where they raised three children, now all in their 30s. Everyone else pays between $1,200 and $1,250 per month.

Chu said it will be impossible for them to find comparable housing in the neighborhood, which is being hemmed in by an increasing number of luxury developments like the Ink Block complex, where apartments rent for upwards of $6,000 a month. Condo units under construction in the complex are going for as much as $2 million.

“Even if we sell the building, for the money we get, I will not be able to get a three bedroom place in the area,’’ Chu said. “That’s to rent, never mind about buying; I will not be able to buy a place in the area. It’s not even a matter of whether or not people are willing [to move], it’s just that there’s a housing crisis. Where do they go?’’

With the June 30 deadline passed, Chu’s brothers have begun the process of evicting tenants. Their July rent payments — as well as security deposits — were returned to them. The matter is scheduled for an Aug. 10 hearing in Boston Housing Court.

Paul W. Chu, Lam Chung Chu’s brother, said that when his family bought the building in the 1980s, the area “had a bad reputation.’’ Now that it’s transformed, he got an offer from a cash buyer that proved too hard to pass up.

“Somebody came in and gave us a good price,’’ Paul Chu said. “And it’s about time to move on.’’

Because the tenants have no lease agreements and live there on a month-to-month basis, Paul Chu said, the 30-days notice complied with state guidelines. Still, he called the current tenants “really good’’ and acknowledged he feels somewhat conflicted over the sale and the tenants’ legal challenges. If the building doesn’t sell, Chu said, he may still apply with the city to convert the apartments to condominiums.

“We might apply for condos just for convenience,’’ he said. “I can’t handle that building too long.’’

The city’s Department of Neighborhood Development is aware of the pending sale of the building and has offered to assist residents, a spokeswoman said. If the tenants are evicted and their units converted to condos, the spokeswoman said they would be entitled to specific protections under the city’s condo conversion laws, including being given more time to move out, and a relocation stipend from the landlord.

“There are many eviction cases especially right now, especially in these types of row houses... There’s a lot of development; tenants in a lot of neighborhoods in Boston are feeling a lot pressure,’’ said Bethany Li, an attorney with Greater Boston Legal Services who is advising the Harrison Avenue tenants. “People can decide to sell their properties when they want; they just have to do it the proper way.’’

Katheleen Conti can be reached at kconti@globe.com. Follow her on Twitter @GlobeKConti.