TPA, but not IL-4, induces PKC-dependent phosphorylation of ERK.

Purified peripheral blood B-CLL cells from patient 1 were incubated (A) for different times with 100 nM TPA and 10 ng/mL IL-4, (B) for 20 minutes with 100 nM TPA after preincubation for 1 hour with 5 μM BisI, and (C) with different concentrations of TPA for 20 minutes. Then cells were harvested and lysed, and phosphorylated forms of ERK (P-ERK) were analyzed by Western blot. (D) Cells from patients 1 (●), 2 (■), and 3 (⧫) were incubated for 48 hours with different doses of TPA in the presence of 10 μM dexamethasone, and cell viability was determined by flow cytometry. Results are represented as the mean ± SD from one experiment performed in duplicate.