CD44 down-regulation induces the expression of p21 and down-regulates the expression of major cell cycle regulatory protein-cyclin D1. (A/B) Increased p21 mRNA/protein expression in CD44 silenced K562 cells. (C) The relative protein expression of p21 compared to GAPDH. (D/E) Decreased cyclin D1 mRNA/protein expression in K562 cells after CD44 interference. (F) The relative protein expression of cyclin D1 compared to GAPDH. (G/H) Unchanged protein expression of Bcl-xl. For real-time quantitative PCR and western blotting, GAPDH was used as an internal control. *, P < 0.05, **, P < 0.01, compared with the control.