If you had any doubt as to whether tobacco was still a winning business proposition in America in 2019, you should look no further than Juul. The SF-based e-cigarette brand just inked a deal to buy 123 Mission Street, a 28-story office tower with 363,000 square feet of highly valuable real estate.

The company didn't disclose the details of the deal, but a local real estate data firm tells the Chronicle that the building might have sold for as much as $400 million. And this means that Juul is expanding fast if they need five times as much office space as they currently have at their Pier 70 headquarters.

Speaking to the paper's Editorial Board earlier this month, Juul CEO Kevin Burns insisted that the company was committed to staying in San Francisco, despite political pushback about the products that they sell. "San Francisco is our home... We have 1,200 employees in San Francisco, a huge talent base in San Francisco. We want to be a resident, and I’m hopeful we’ll find a way to be a resident," Burns said. The interview followed a pair of proposed bills to crack down on vaping, and a comment from Supervisor Shamann Walton saying, "We don't want [Juul] in our city."

And Juul says it plans to keep its headquarters at Pier 70, and use the new building as expansion space. The company also has offices in Mountain View, Austin, and New York.

A spokesman for the company said Tuesday, "We have always been a proud San Francisco-based company and remain committed to serving the community as we focus on helping adult smokers switch from combustible cigarettes — the leading cause of preventable death — and combating underage use."

The sellers of 123 Mission are Northwood Investors of New York, who just bought the building a year ago for $290 million.