Although some RNases with ribonucleolytic activity exhibit direct cytotoxicity to kill cancer cells,[40] wild‐type RNase1 has been shown to be noncytotoxic to cancer cells.[41] Because the ribonucleolytic activity of RNases is inhibited by RNase inhibitors (RIs), which block the digestion of intracellular RNAs by RNases,[12, 42] most anticancer RNases must be engineered to evade RI binding. Here, RNASE1 is linked to cancer.