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.