To further determine the possible molecular mechanisms of cell cycle alteration and apoptosis induction mediated by SHP2 inhibitors, we used the immunoblotting analysis and found that SHP099 and RMC-4550 treatment increased the expression of apoptosis-related protein cleaved caspase-3, BAK, and cell cycle inhibitor P21 of MM cells in a concentration-dependent manner (Figures 4A,B). Here, BAK1 is linked to Miyoshi myopathy.