FIG. 7.

Analysis of cyclin-Rb axis regulation and D-type cyclin function in cyclinD1-deficient CGNPs treated with Shh. A Western blot analysis of cell cycle regulatory protein response to Shh treatment in cyclinD1-deficient (−/−) mice and heterozygous (+/−) or wild-type (+/+) littermates is shown. (A) Western blot assay for hyperphosphorylated (PpRb) Rb protein, cyclin E, PCNA, and cyclin D3 after 24 h of Shh treatment. Note the equivalent responses of Rb hyperphosphorylation, cyclin E, and PCNA levels to Shh in all samples. (B) Intact D-type cyclin function in cyclinD1^−/− CGNPs treated with Shh. CGNPs from cyclinD1 −/−, +/−, or +/+ littermates were treated with Shh for 15 h. Phosphorylation of Rb on serine-780 was analyzed by Western blotting (top). The membrane was stripped and reblotted for total Rb protein (bottom).