Figure 6.

K5 downregulates GRP78 via VDAC and ERK phosphorylation. (a) K5 downregulates p-ERK expression. SGC-7901 cells were cultured with or without 640 nM K5 for 15, 30, or 60 min under normoxia (N) or hypoxia (H). The protein level of p-ERK and ERK were detected by western blotting. (b) Immunoblot assays of p-ERK, ERK, and GRP78 proteins from SGC-7901 cells cultured in the presence of 10 μM U0126 for 12 h. (c and d) VDAC is primarily responsible for the downregulation of p-ERK and GRP78 expression by K5. Immunoblotting assays of VDAC, GRP78, p-ERK, and ERK proteins from SGC-7901 cells transfected with siRNA specific to VDAC or a scrambled control (siCTRL) for 24 h and then treated with 640 nM K5 for another 24 h (c) or 60 min (d) under hypoxia