The human ASH2L gene encodes a 628 amino acid protein known as ASH2L1, or isoform 1, which contains a nuclear localization signal and PHD finger motif, suggesting that the gene product functions as a transcription regulator. Alternative splicing results in a shorter isoform 2, designated ASH2L2, which is missing the first 94 amino acid residues found in ASH2L1. Human ASH2L proteins are 60% homologous to Drosophila ash2, which positively regulates expression of certain genes in early development, and contain similar, but not identical, domains, including a zinc finger motif. ASH2L is highly expressed in fetal liver, testis and leukemia cell lines with erythroid and megakaryocytic potential, such as K562, Hel and Dami. Differentiation inducers (e.g. phorbol ester and hemin) cause different expression patterns in these cells lines, suggesting that ASH2L plays a role in hematopoiesis and is associated with particular types of leukemia.