Panel A: DNMT1, DNMT3b, XPA, and DNA-PKcs levels were increased in nuclear extracts prepared from late passage ERK1-GFP cells, relative to early passage ERK1-GFP cells and vector controls. DNMT1 consistently exhibited multiple bands immunoreacting with anti-DNMT1 antibody in late passage ERK1-GFP cells. Lamin a/c was used as a loading control. Panel B: Graph illustrates pooled results from three independent experiments for early (white) and late (black) passage ERK1-GFP cells, relative to vector control (referenced as fold change value of 1). Values represent mean ± se (n = 3). *Significantly different from vector control. General methods for Western blot analysis can be found in .