Figure 3.

Casein kinase II specific inhibitors prevent phosphorylation of Pax3 at Ser205. Bacterially expressed and purified GST-Pax3 was phosphorylated in vitro using proliferating mouse primary myoblast total cell extract that had been previously incubated in the presence or absence of increasing amounts of the commonly used CK2 inhibitors DRB (top panel) or heparin (bottom panel), as described in the Experimental Procedures. Western blot analysis was performed using our anti-Pax3(p205) antibody (12) to visualize the phosphorylation status of Ser205 and Coomassie staining was performed to confirm the presence of equal amounts of protein. The numbers under the gels indicate the percent maximal phosphorylation, determined relative to the control, providing an approximate IC₅₀ of 10 μM and 1 μM for DRB and Heparin, respectively.