Stiefel Laboratories, Inc. has enlisted the advisory arm of Blackstone Group for assistance with the sale of the company, according to a source. The privately held U.S. pharmaceutical company is the world’s largest independent dermatology company and its value is estimated at more than $3 billion. Blackstone, which owns a substantial minority stake in Stiefel, has begun contacting parties regarding the sale, according to a source. The Wall Street Journal first reported that Stiefel was ...