Figure 1.

p53 inactivation protects some cells from the negative consequences of deletion of Dicer. The p53 tumor suppressor responds to impaired miRNA processing by inducing senescence, cell cycle arrest, or apoptosis. Non-hematopoietic cells that harbor inactivated p53 can survive and grow (albeit possibly more slowly) in the absence of Dicer. In contrast, hematopoietic cells are extremely sensitive to Dicer loss and rapidly undergo apoptosis, regardless of p53 status. *Co-inactivation of the Rb pathway with p53 results in synthetic lethality.