Figure 6.

Anti-countin antibodies decrease myosin phosphorylation and increase the basal level of myosin assembly. (A) Ax4 cells were starved in the presence of preimmune or anti-countin antibodies. Samples were collected at 6 h, and a Western blot of the samples was stained with anti-phosphothreonine or anti-myosin II heavy chain antibodies. WT, untreated Ax4 cells; HS1, untreated myosin II heavy chain null cells; PI, Ax4 cells exposed to preimmune antibodies; I, Ax4 cell exposed to anti-countin antibodies. Arrow indicates the 210-kDa myosin II heavy chain. (B) Ax4 cells were harvested at 6 h and stimulated with cAMP, and cytoskeletons were isolated at the times indicated in seconds after cAMP stimulation. For each treatment, the band shown is the 210-kDa myosin heavy chain from a Coomassie-stained 12% SDS-polyacrylamide gel of the cytoskeletons.