SMYD3 is a gene that is over-expressed in the majority of colorectal carcinomas and hepatocellular carcinomas. SMYD3 forms a complex with RNA polymerase II through an interaction with the RNA helicase HELZ and transactivates a set of genes that included oncogenes, homeobox genes and genes associated with cell-cycle regulation. SMYD3 binds to a motif, 5'-CCCTCC-3', present in the promoter region of downstream genes such as Nkx2.8. The SET domain of SMYD3 shows histone H3-lysine 4 (H3-K4)-specific methyltransferase activity, which is enhanced in the presence of the heat-shock protein HSP90A.