MAPK8 and Blackfan-Diamond anemia: Since the tumor suppressor P53 is a master regulator of apoptosis in many cell types, including erythroblasts24, and mutations in the ribosomal protein genes cause erythroid cell death in patients with Diamond-Blackfan anemia via P53 activation11, we examined whether P53 is involved in JNK inhibition-induced apoptosis in human erythroblasts.