PCNP is a novel 178 amino acid nuclear protein implied to play a role in cell cycle regulation and tumorigenesis. PCNP is ubiquitinated post-translationally by NIRF (Np95/ICBP90-like RING finger protein), a ubiquitin ligase. Existing as three isoforms produced by alternative splicing events, PCNP is encoded by a gene mapping to human chromosome 3q12.3. Chromosome 3 houses over 1,100 genes, including a chemokine receptor (CKR) gene cluster and a variety of human cancer-related gene loci. Key tumor suppressing genes on chromosome 3 include those that encode the apoptosis mediator RASSF1, the cell migration regulator HYAL1 and the angiogenesis suppressor SEMA3B. Marfan Syndrome, porphyria, von Hippel-Lindau syndrome, osteogenesis imperfecta and Charcot-Marie-Tooth Disease are a few of the numerous genetic diseases associated with chromosome 3