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. 2000 Oct 1;28(19):3771–3778. doi: 10.1093/nar/28.19.3771

Figure 2.

Figure 2

Southern blot analysis of DNA from TK–APRT– colonies isolated from JAM1-41 (ERCC1+) and JAM1-77a (ERCC1–) cells. The structure of the tandem duplication along with the locations of BamHI sites is shown in Figure 1A. The downstream copy of APRT in the parental structure gives rise to a 4.0 kb fragment. Crossover products retain only the downstream copy of the APRT gene. The hybridization probe corresponds to the 4.0 kb BamHI fragment of the APRT gene. Lanes 1 and 25 show DNA from a control cell line that has a single copy of the APRT gene and gives a band at 4.0 kb; lanes 2 and 24 show DNA from the parent cell line, which gives rise to bands at 4.0 and 12.3 kb. Lanes 3–12 are TK–APRT– colonies from JAM1-41; lanes 13–23 are TK–APRT– colonies from JAM1-77a.