RPS14 and Down syndrome: Activation of p53 has been shown to occur selectively in erythroid cells differentiated from human HSC with shRNA-based knockdown of RPS14. 24 Induction of p53 resulted in erythroid-specific accumulation of p21, cell cycle arrest and apoptosis, consistent with the failure of erythropoiesis observed in the 5q- syndrome.24 Inhibition of p53 using pifithrin-α in culture rescued the erythroid defect, suggesting that p53 activation may represent a therapeutic target in MDS with del(5q).24