Supporting the role of p53 in cell cycle inhibition, AcSDKP inhibits cell cycle progression in normal cells, but AcSDKP does not suppress progression in chronic myeloid leukemia (CML) progenitors in long-term culture (Cashman et al., 1994) as these cells frequently exhibit p53 deficiency (Chen et al., 1990; Feinstein et al., 1991; Bi et al., 1992). Here, TMSB4X is linked to chronic myelogenous leukemia, BCR-ABL1 positive.