This gene encodes a member of a family of guanosine triphosphate (GTP)-binding proteins that associate with microtubules and are involved in vesicular transport. The encoded protein functions in the development of megakaryocytes. Alternative splicing results in multiple transcript variants. [provided by RefSeq, May 2013]

C1 Inactivator is a highly glycosylated plasma protein involved in the regulation of the complement cascade. Its protein inhibits activated C1r and C1s of the first complement component and thus regulates complement activation. Deficiency of this protein is associated with hereditary angioneurotic oedema (HANE). Alternative splicing results in multiple transcript variants encoding the same isoform.

Involved in the homologous recombination repair (HRR) pathway of double-stranded DNA, thought to repair chromosomal fragmentation, translocations and deletions. Plays a role in regulating mitochondrial DNA copy number under conditions of oxidative stress in the presence of RAD51 and RAD51C.

HOXA9 is a transcription factor with a central role in both haemopoiesis and leukaemia. High levels of HOXA9 expression in haemopoietic cells is a characteristic feature of acute myeloid leukaemia (AML), and may be sufficient to cause this disease. Overexpression of Hoxa 9 markedly expands hematopoietic stem cells. HOXA9 expression changes dramatically with age - a uniformly low level of expression during early adulthood is replaced by a frequently very high expression in adults over sixty.

NPR2 encodes natriuretic peptide receptor B, one of two integral membrane receptors for natriuretic peptides. Both NPR1 and NPR2 contain five functional domains: an extracellular ligand binding domain, a single membrane spanning region, and intracellularly a protein kinase homology domain), a helical hinge region involved in oligomerization, and a carboxyl terminal guanylyl cyclase catalytic domain. NPR2 is the primary receptor for C type natriuretic peptide (CNP), which upon ligand binding

HOXA5 upregulates both p53 promoter-reporter constructs and endogenous p53 synthesis, leading to apoptosis. HOXA5 is detectable in approximately one-third of primary tumors. Lack of HOXA5 expression strongly correlates with methylation of its promoter region, suggesting a causal role for methylation in the silencing of HOXA5 gene expression. HOXA5 expression is an important step in tumorigenesis and loss of expression of p53 in human breast cancer may be primarily due to lack of expression of