PLK1 and gastric cancer: Similarly, many studies have shown that abundant CD169+ macrophages in lymph nodes are positively correlated to the amount of CD8+ T cells in the tumor, and favorable patient overall survival (OS) in bladder cancer, colon cancer, gastric cancer, and malignant melanoma [26,29,30,31] However, Singh and Choi recently unraveled that sinus CD169+ macrophages can promote the survival of melanoma cells via mitotic polo-like kinase 1 (PLK1) phosphorylation at the subcapsular sinus region [32].