The effects of decreased expression of ribosomal proteins and p53 activation on myeloid differentiation. Top, reduced expression of Rps19 and Rps14, ribosomal proteins affected in Diamond-Blackfan anemia and 5q− syndrome, respectively, selectively affects erythroid differentiation from human CD34⁺ progenitors. Bottom left, treatment with nutlin-3, which results in p53 activation, mimics the effect of reduced ribosomal protein expression. Bottom right, pifithrin-α, an inhibitor of p53 activation, rescues the effect of reduced ribosomal protein expression on erythropoiesis. (Professional illustration by Debra T. Dartez.)