Embattled medical testing company Theranos today said that it’s closing down clinical labs and Theranos Wellness Centers and thus cutting 340 employees in Arizona, California, and Pennsylvania. It had 790 employees in August, meaning the layoffs affect 43 percent of the company’s workforce.

“We will return our undivided attention to our miniLab platform,” Theranos founder Elizabeth Holmes wrote in an open letter. “Our ultimate goal is to commercialize miniaturized, automated laboratories capable of small-volume sample testing, with an emphasis on vulnerable patient populations, including oncology, pediatrics, and intensive care.”

The move follows the Wall Street Journal’s extensive reporting on Theranos’ technology and practices. In July Theranos said it would take steps to fix issues raised by the U.S. Centers for Medicare & Medicaid Services.

Investors include ATA Ventures, BlueCross BlueShield Venture Partners, Draper Fisher Jurvetson, and Oracle cofounder Larry Ellison.

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