In the present study, we identified niclosamide, an FDA-approved anti-helminthic drug [27,28], as not only a potent inhibitor of macropinocytosis but also an inducer of ferroptosis in colon cancer cells, thus underscoring the potential of this drug as an anticancer agent, especially for cancers associated with oncogenic changes in KRAS and p53. Here, KRAS is linked to cancer.