ASXL1 and leukemia: The leukemia cell lines K562 and Kasumi-1 harbor endogenous ASXL1 mutations, generating a nonsense mutation Y591X and a frameshift mutation G646Wfs*12, leading to the premature termination of ASXL1 protein at codon 590 and 646, respectively (Figs. 1B, S1A and S1B).