TP53 and autoimmune thrombocytopenic purpura: For example, PDGF-BB decreased SA-β-gal positive cells and the expression of P53 and P21 while enhancing proliferative potential in senescent human dermal fibroblasts (Bae et al., 2016) and mesenchymal stem cells (MSCs) derived from immune thrombocytopenia patients (Zhang et al., 2016).