SMYD3 (SET and MYND domain containing 3) is a histone methyltransferase that plays a role in transcriptional regulation as a member of an RNA polymerase complex. The introduction of SMYD3 enhanced cell growth and the histone methyltransferase activity of SMYD3 involved in the proliferation of cancer cells. A variable number of tandems repeat polymorphism in an E2F-1 binding element in the 5-prime flanking region of SMYD3 is a risk factor for human cancers.