FIG. 8.

Regulation of c-myc and PR protein expression in T47D cells stably expressing wild-type or mutant S294A PR-B. (A) Duplicate cultures of T47D-YB cells stably expressing wild-type PR or PR-negative T47D cells stably expressing S294A mutant PR were placed in serum-free medium for 24 h prior to treatment without or with EtOH vehicle control, EGF (30 ng/ml), R5020 (10 nM), or EGF plus R5020 for 12 h; levels of c-myc protein in whole-cell lysates were determined with specific antibodies. Numbers above the lanes indicate fold increases over EtOH-treated controls as measured by densitometric analysis of immunoblots. (B) Duplicate cultures of T47D cells stably expressing either wild-type or mutant S294A PR-B were treated as described in the legend to panel A, except that treatment continued for 6 h and PR-B protein levels in whole-cell lysates were measured using PR monoclonal antibodies.