Wolf-Hirschhorn syndrome candidate 1-like protein 1 (WHSC1L1), also known as histone-lysine N-methyltransferase NSD3, is a SET domaincontaining histone methyltransferase protein that methylates histone H3 on lysine 4 (H3K4me) and lysine 27 (H3K27me) (1). Methylation of histone H3 lysine 4 is associated with transcriptional activation, while methylation of histone H3 lysine 27 is associated with transcriptional repression. WHSC1L1 can function as an oncogene or a tumor suppressor protein, depending on cell context, and has been shown to regulate expression of a number of genes associated with cell cycle (2). Amplification and/or increased expression of WHSC1L1 in breast, lung, and liver cancer increases growth and survival, and is associated with poor prognosis (2-5). In addition, the NSD3 gene has been found fused with the nuclear pore complex protein NUP98 gene in acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL), and fused with the NUT gene in NUT midline carcinomas (6-10).
