CBX2 knockdown induces p21 and p14^ARF expression and p21 knockdown partially rescues the CBX2 knockdown phenotype. (A) qPCR analysis of mRNA levels in SCR and CBX2 knockdown cells from liquid cultures at day 4 after transduction. (B) Western blot analysis of shSCR/shCBX2-expressing cells at day 2 after transduction. (C) Western blot analysis of SCR, CBX2, BMI1, and MEL18 shRNA-expressing cells at day 10 after transduction. (D) CFC analysis of freshly transduced and replates of cells expressing SCR^GFP/SCR^CFP, p21^GFP/SCR^CFP, SCR^GFP/CBX2^CFP, or p21^GFP/CBX2^CFP shRNAs.