NEW YORK (AP) - Troubled blood-testing startup Theranos acknowledged that it is under investigation by several regulators and agencies.

NEW YORK (AP) Troubled blood-testing startup Theranos acknowledged that it is under investigation by several regulators and agencies.

The investigations and inspections come after a series of articles by The Wall Street Journal in which former employees said the company's blood tests, which use a few drops of blood, were unreliable. Theranos has said the articles were wrong.

In a letter Monday, Theranos said investigations or inspections were opened by the Centers for Medicare and Medicaid Services, the Securities Exchange Commission and the U.S. Attorney's Office for the Northern District of California. It said investigations by the Food and Drug Administration and the Departments of Health in Arizona and Pennsylvania were closed successfully.

Theranos, based in Pal Alto, California, said it is cooperating fully with all investigations.