CDKN1A and acute myeloid leukemia: To this end, AML-12 cells, a normal mouse hepatocyte line, were treated with various doses of Dox, and 0.2 μM Dox was confirmed as an appropriate dose on the basis of cell viability (Figure 5A) as well as significant senescence-related changes in the expression of p21 and phosphorylated histone H2AX (γH2AX) (Figure 5B,C).