Role for MAPKs in growth-dependent SAC1 translocation to the ER. (A–C) Localization of the endogenous SAC1 in NIH3T3 cells was analyzed by immunofluorescence microscopy using polyclonal anti-SAC1 antibodies. Quiescent cells were stimulated by the addition of 10% serum (C) or a mix of EGF/basic FGF/PDGF (A) or individual growth factors (B) for 1 h at 37°C. (C) Quiescent cells were incubated with 10 μM of the MEK1/2 inhibitor UO126, 10 μM of the JNK MAPK inhibitor SP600125, or 10 μM p38 MAPK before stimulation with 10% serum. Bar, 15 μm.