MKI67 and laryngeal carcinoma: They also found that expression of proliferating cell nuclear antigen (PCNA), a DNA polymerase accessory protein, and Ki67, a large molecular weight protein whose expression is restricted to the G1 through M phases of the cell cycle and whose function remains unknown, were positively associated with poorly differentiated laryngeal carcinoma and laryngeal carcinoma that was associated with lymph node metastasis.