Figure 1. Cdk3 is overexpressed in glioblastoma tissue and various cancer cell lines.

(A, top) Endogenous cdk3 and cyclin C protein levels were detected in 15 different cell lines. Cells were harvested and proteins (40 μg) were resolved by SDS-PAGE and detected by Western blotting using anti-cdk3 or anti-cyclin C. (A, bottom) Endogenous cdk3 activity was examined by immunoprecipitation with anti-cdk3 and subjected to a kinase assay using histone H1 as substrate. Kinase reactions were analyzed by SDS-PAGE followed by autoradiography. (B) Immunofluorescent staining and confocal microscopy were used to detect the expression of cdk3 in tissue from 35 cases of human brain glioblastoma, 2 cases of normal cerebrum tissue that were adjacent to cancer tissue, and 3 cases of non-neoplastic normal cerebrum tissue. Cdk3 was detected by immunofluorescent staining using anti-cdk3 as the primary antibody and a Cy3-conjugated donkey anti-rabbit antibody as the secondary. The intensity score of fluorescence from each sample was determined and the horizontal lines indicate the median of glioblastoma or non-cancer tissue samples. Significant differences were evaluated using the Mann-Whitney U test (*, p < 0.01). Pictures from representative cases are shown in the bottom panels.