Fig. 1. TPA-induced downregulation of PKC. Control (empty-vector-transfected) RBL cells (A,B), RBL-Syt II^- cells (A) and RBL-Syt III^- cells (B) were incubated with or without TPA (50 nM) for 6 hours. Whole lysates (40 µg protein) were resolved by SDS-PAGE and immunoblotted. The cellular level of PKC was determined by western blot analysis using anti PKC antibodies. The level of Syt II was determined using the monoclonal antibody 8G2B directed against the N-terminus of Syt II. The cellular level of Syt III was determined using a rabbit polyclonal serum directed against the cytoplasmic domain of Syt III. The cellular level of actin was determined to judge for equal loading. Data represent one of three separate experiments.