Silicon Valley startup Theranos Inc. is fighting for its life after regulators decided to revoke its license to operate a lab in California because of unsafe practices and to ban founder Elizabeth Holmes from the blood-testing business for at least two years.

The sanctions were laid out in a letter to Theranos released Friday by the agency that oversees U.S. labs, the Centers for Medicare and Medicaid Services. Theranos said it is still seeking to resolve its issues with the regulator.

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