HPR proficiency in cells defective in XPG. (A) HPR efficiency in extracts derived from HeLa cells and two XPG-deficient cell lines, AG08802 and GM16024. The repair values were determined from at least three independent HPR assays. (B) AG08802 cells are partially defective in HPR. HPR assays were performed by incubating nuclear extracts derived from AG08802 or HeLa cells with individual hairpin substrates, as indicated. The resulting DNA products were digested with BglI and BsrBI and subjected to Southern blot analysis using a probe (blue bar) specifically annealing to the nicked strand near the BglI site. Schematic diagrams for the V- or C-strand hairpin repair are depicted in the left or right side of the gel, respectively, with repair products being highlighted by a red rectangle.