Proliferating Cell Nuclear Antigen (PCNA)

PCNA, also known as cyclin, is a 36 kD nonhistone nuclear protein that plays a fundamental role in the initiation of cell proliferation. PCNA is a cell cycle-regulated protein that preferentially occurs in dividing cells and is undetectable or present in small amounts in resting cells. Immunoperoxidase staining for PCNA in benign tissues has revealed positive nuclear staining in normal colonic crypt epithelium, gastric glandular cells, germinal center cells of lymph node, basal cells of skin, and renal tubular epithelial cells. The monoclonal antibody to PCNA might be an acceptable alternative to Ki-67 labeling in routinely processed tissues. This antibody stains PCNA in the nucleus of proliferating cells.