Privately held , which maintains a major research and development facility in RTP, reportedly has put itself up for sale.

Interested buyers reportedly include GlaxoSmithKline, which operates its U.S. headquarters in RTP, as well as Johnson & Johnson, Novartis, Abbott Laboratories, Sanofi-Aventis and Allergan.

The Wall Street Journal and Reuters reported Friday that Stiefel has asked Blackstone Group to seek offers.

Stiefel is based in Coral Gables, Fla. The company focuses on dermatology products.

Blackstone owns a minority stake in Stiefel. It invested $500 million in Stiefel two years ago, according to Private Equity Wire.

“It’s definitely for sale,” a source told Reuters. “They (Blackstone) have just started contacting parties.”

Reuters estimated that the company could be worth $3 billion or more.

Stiefel is a 160-year-old venture.