UV sensitivity, UV-UDS, UV-RRS, and TFIIH incision/excision activity.
UV survival, UV-UDS, and UV-RRS assays were performed as described previously [21,30]. For UV-RRS, average values from the representative experiment containing two wt, three XpdTTD/TTD, two XpdTTD/XPCS, and one XpdTTD/XP cell line are presented. The ~48% UV-UDS value presented in this study for XpdTTD/TTD cells differs from our previously published data of 25% UV-UDS [21], possibly because of the high variability intrinsic to the assay or routine variations in the cell culture conditions. For the incision/excision activity assay, recombinant TFIIH was prepared and assayed as described previously [27].