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. Here, PCNA is linked to laryngeal carcinoma.