Figure 4.

Inhibition by Dad of Tkv-induced phosphorylation of Mad. (A) Inhibition by Dad of Mad phosphorylation was examined by [³²P]orthophosphate labeling. The experiment was performed as shown in Figure 3A. Expression levels of proteins were monitored by Western blotting. (B) Intensities of bands were determined with a densitometer, and the ratio between [³²P]orthophosphate incorporation and protein expression level was calculated. (C) Effect of Dad on Tkv-induced Mad phosphorylation was examined. Anti-phosphoserine antibody was used as in Figure 3B. Expression levels of the proteins were monitored by Western blotting.