CAK is not essential for the recruitment of XPC, TFIIH, XPA and XPG to DNA damage sites.

<p>(<b>A</b>) Recruitment of XPC, TFIIH (XPB, p62 and MAT1), XPA and XPG to locally damaged DNA sites is not affected by 1-NMPP1-mediated CAK inhibition. HCT116-Cdk7^as/as cells were grown on coverslips and pretreated with 1-NMPP1 or DMSO for 14 h. The cells were then UV irradiated at 100 J/m² through a 5 µm isopore polycarbonate filter, and incubated for another 1 h in fresh medium similar to the pretreatment. The cells were subsequently fixed with 2% paraformaldehyde and processed for immunofluorescence double labeling. (<b>B</b>) The quantitative estimation of repair factor recruitment was based on the number of foci/100 nuclei from five different microscopic fields. Bars indicate mean ± S.E. for the indicated antibody staining. Symbol * indicates significant difference (p<0.05) from NHF.