FIGURE 7.

ErbB2 kinase activity but not PKC-α are required for PMA-induced ERK phosphorylation. A, SKBR-3 cells seeded in 6-well plates were treated with DMSO (vehicle) or the indicated concentrations of PMA for 8 h. 25-μg aliquots of Triton X-100 lysate proteins were subjected to immunoblotting for p-ERK 1/2, total ERK 1/2, and β-actin (loading control). B, SKBR-3 cells were transfected with a non-targeting siRNA (control) or PKC-α-specific siRNAs (a smartpool or siRNA no. 2) for 48 h, treated without or with Lapatinib (1 μm) for 1 h, and further incubated in the presence of DMSO (vehicle control) or PMA (100 nm) for 1 h. Western blotting with anti-ErbB2-pY-1248, anti-ErbB2, anti-PKC-α, anti-p-ERK 1/2, anti-ERK 1/2, and anti-β-actin (loading control) antibodies was carried out as in A.