FIG. 3.

RT-PCR analysis for Aprt expression. RNA samples were isolated from the parental MC109 cell line (109), a 5-azc-dC-induced DAP-resistant clone, 109AzcD4 (D4), an unstable (S1) and a stable (S2) subclone, a stable FA-selected subclone (F12), and two spontaneous revertants (R2 and R3) isolated from the S1 subclone. Expression from the cotransfected bacterial neo gene was used to confirm that equivalent amounts of RNA were used. See Materials and Methods for more details on methods and Table 2 and text for more details on cell lines.