Knockdown of RRM2 through specific small interfering RNA (siRNA) displayed effective antitumor activity in various solid tumors, like head and neck cancer [30], including oral squamous cell carcinoma [31], ovarian cancer [32], gastric adenocarcinoma [33], hepatocellular carcinoma [34], and colorectal cancers [35]. Here, RRM2 is linked to colorectal cancer.