PROK1 and colorectal cancer: Lymph node metastasis was observed in 100 of 249 (40.2%) colorectal cancer patients with negative PROK1 expression in the primary lesion, whereas 96 of 142 (67.6%) patients with positive PROK1 expression, demonstrating a significant increase in lymphatic metastasis with PROK1 expression in the primary lesion (Table 1).