Monxo Lopez is a popular man. He wishes he were not.

Total strangers hound him, calling, writing and knocking on his door, all with the same question: Does he want to sell his red brick rowhouse nestled on a historic South Bronx block in Mott Haven? When he complained to a friend who worked in real estate, the friend replied: “You know, you can get a million and a half.”

Given that he paid $400,000 for his four-story house in 2004, he could make a tidy profit. Others in his neighborhood have received similar offers, thanks to the rush of gentrification, development and speculation transforming Mott Haven and Port Morris, immediately south of it. Now branded as hot, he’d rather it was not.

“I come from Puerto Rico, where my sister lives in the same house where we grew up,” said Mr. Lopez, who lives with his wife, Libertad Guerra, and their 4-year-old daughter Xul. “We don’t see this as an investment, we see this as our home. I have no desire to sell.”

It’s not surprising that his house attracts attention, since it is on a stretch of Alexander Avenue north of East 138th Street that was once known as “Irish Fifth Avenue” for the doctors and lawyers who settled there in the early 20th century. After enduring decades of abandonment, blight and crime, the area has begun to bounce back. The fear is it may bounce completely out of the reach of longtime residents who are being pressured to sell, or renters whose landlords are increasing rents or harassing them to leave.