Figure 3.

The inhibition of calpain stabilizes RBL1/p107 protein levels, which is not affected by either proteosomal or lysosomal inhibitors. (A–C). RBL1/p107 levels and RBL1/p107 phosphorylation at Ser975 (C) were determined by immunoblot in A549 cells and MSTO-221H cells (C) preincubated with the proteasome inhibitor MG-132 (1 µM) (A), the lysosome inhibitor bafilomycin A1 (0.1 µM) (B) or the calpain inhibitor ALLN (100 µM) (C), for 1 h and then treated for 16 h with 12.5 µM AKTi VIII alone or in combination with MG-132 (A), bafilomycin A1 (B), or ALLN (C). Quantification was performed by densitometric analysis using the ImageJ program and expressed as % of control. All experiments were performed three times.