SBDS expression during erythroid differentiation. (A) Real-time RNA quantitative PCR was used to analyze daily SBDS mRNA expression in CD133⁺ HSC/Ps after induction of erythroid differentiation. The experiment was performed in triplicate. The ACTB gene was used as an internal control. (B) SBDS mRNA expression by RNA quantitative PCR was also determined in wild-type K562 cells after induction of erythroid differentiation by hemin. Three separate experiments were conducted in triplicate. (C) SBDS protein expression in hemin-induced K562 cells by Western blotting (representative blot of 3 experiments).