Mcl-1 degradation by Bay 61–3606 is independent of Syk.

(A) MCF-7 cells were transfected with scrambled (siCTL) or Syk siRNA (siSyk) for 48 h, and expression of Syk and Mcl-1 was analyzed by Western blotting. (B) MCF-7 cells were exposed to Syk inhibitors for 6 h and Mcl-1 expression was assessed by Western blotting. (C) Three, breast-cancer cell lines were exposed to TRAIL (50 ng/ml) for 6 h, Syk mRNA expression was analyzed by RT-PCR (lower), and phosphorylation of Syk and expression of Mcl-1 were analyzed by Western blotting(upper). (D) T47D cells were exposed to increasing concentrations of Bay 61–3606 for 6 h, and expression of Mcl-1 was analyzed by Western blotting.