PRL-2 (Protein-tyrosine phosphatase of regenerating liver 2), also known as PTP4A2 (Protein tyrosine phosphatase type IVA, member 2), is a member of PTP family and has an important function in controlling cell growth. PRL-2 phosphatases may be multifunctional enzymes with diverse roles in a variety of tissue and cell types. The phosphatase of regenerating liver (PRL) family, comprising PRL-1, PRL-2 and PRL-3, is a group of prenylated phosphatases that are candidate cancer biomarkers and therapeutic targets. PRL-1, PRL-2, and PRL-3 represent a novel class of protein-tyrosine phosphatase with a C-terminal prenylation motif. They are three closely related intracellular enzymes that possess the PTP active site signature sequence CX 5R. The PRL-2 mRNA is elevated in primary breast tumors relative to matched normal tissue, and also dramatically elevated in metastatic lymph nodes compared with primary tumors. PRL-2 plays a role in breast cancer progression. PRL-2 is a pathogenic molecule in hematopoietic malignancies and it has potential as a novel therapeutic target.

HNMT (Histamine N-methyltransferase) is a Protein Coding gene. This gene encodes the first enzyme which is found in the cytosol and uses S-adenosyl-L-methionine as the methyl donor. HNMT, the major enzyme for the metabolism of histamine in the rat brain, is potently inhibited by 9-amino-1,2,3,4-tetrahydroacridine (tacrine). Methylation is an important pathway in the biotransformation of many drugs, neurotransmitters, and xenobiotic compounds. Histamine N-methyltransferase (HNMT) catalyzes the N tau-methylation of histamine and structurally related compounds. Histamine N-methyltransferase (HNMT) is believed to be the sole pathway for termination of the neurotransmitter action of histamine in the mammalian brain. That highlights the importance of the inclusion of HNMT for genetic testing of individuals presenting with intellectual disability.

PTP4A2, also known as PRL2 or PTPCAAX2, is short for Protein tyrosine phosphatase type IVA 2. This protein exists in cell membrane, cytoplasm,endosome and membrane. PTP4A2 is often farnesylated during post-translational modification. Farnesylation is required for membrane targeting and for interaction with RABGGTB. The unfarnesylated forms are redirected to the nucleus and cytosol. It can stimulate progression from G1 into S phase during mitosis and promotes tumors. It also inhibits geranylgeranyl transferase type II activity by blocking the association between RABGGTA and RABGGTB.