Studies revealing PLK1 overexpression have been done in melanoma [154], non-small cell lung cancer [155], head and neck squamous cell carcinoma [156], ovarian and endometrial cancers [157,158], esophageal squamous cell carcinoma [159], hepatocellular carcinoma [160,161], hepatoblastoma [162], colorectal cancers [163], bladder cancers [2], gastric carcinoma [164], pancreatic cancer and cancer cell lines [165], gliomas [166], breast cancers [167], including triple-negative breast cancer [168], and castration-resistant prostate cancer cell lines [169]. This evidence concerns the gene PLK1 and cancer.