FIGURE 3.

PKCδ null MEFs fail to arrest in G₂/M phase following UV irradiation. A, Western blot displaying PKCδ protein levels in wild-type (WT) and PKCδ null MEF whole cell lysates. α-Tubulin levels are shown as a loading control. B, representative DNA content histograms of wild-type and PKCδ null MEFs before and 18 h after exposure to 30 mJ/cm² UV radiation. C, the percentage of wild-type and PKCδ null MEFs in G₂/M phase of the cell cycle before and after exposure to 30 mJ/cm² UV radiation is displayed. Error bars denote the S.D. from experiments performed in triplicate. *, Student's t test value of p < 0.005. D, the percentage of wild-type and PKCδ null MEFs with G₂/M DNA content at various times following exposure to 30 mJ/cm² UV radiation is displayed. Error bars denote the S.D. from experiments performed in triplicate. #, Student's t test value of p < 0.005. E, wild-type and PKCδ null MEFs were exposed to 10 mJ/cm² UV radiation, treated with 100 ng/ml nocodazole, and stained for phosphorylated histone H3 (Ser¹⁰) and propidium iodide 6 h after UV exposure. Flow cytometry analysis is shown, with the phosphorylated histone H3 (Ser¹⁰)-positive G₂/M DNA content cells circled as the mitotic cells. F, quantitation of mitotic indices from HaCaT cells treated as described for D. **, Student's t test value of p < 0.05.