Figure 1.

ATF3 can be SUMOylated endogenously and in overexpression system. (A) Total lysates from human prostate tissues and prostate cancer cells (LNCaP, PC3, and DU145) were immunoblotted with anti-ATF3 antibody. Cell lysates were probed with a β-actin antibody to control for equal loading; (B) Total lysate of human prostate tissue was immunoblotted with anti-ATF3 antibody (left panel). The empty arrows indicate lower mobility bands consistent with SUMOylated ATF3. The solid arrows indicate non-SUMOylated ATF3. Total lysate of human prostate tissue was first immunoprecipitated by anti-ATF3 antibody and then immunoblotted by either anti-SUMO1 or anti-ATF3 (right panel); (C) ATF3 SUMOylation in vivo in PC3 cells. Lysates of PC3 cells transfected with 3 μg HIS-tagged WT or K42R ATF3 were subjected to Ni²⁺ bead pulldown, followed by anti-ATF3 immunoblotting. The empty arrows indicate SUMOylated ATF3 and the solid arrows indicate non-SUMOylated ATF3. * indicates non-specific band.