The following antibodies were obtained from indicated suppliers: mouse
anti-BrdU FITC (BD Bioscience), mouse anti-p21 (Santa Cruz), mouse anti-BRAF (Santa
Cruz), mouse anti-β-actin (Abcam)19 (link), and mouse anti-p16 was a gift from Dr. Greg Enders.
Immunofluorescence staining and BrdU labeling for cultured cells were performed as
previously described using the antibodies listed above16 (link)18 (link). SA-β-Gal staining was
performed as previously described20 (link).