These reports were followed by additional studies describing the effects of additional small-molecule MTH1 inhibitors or the targeted inhibition of MTH1 via shRNA, siRNA, or CRISPR in a wide variety of cancer cell lines [37,38,39], ostensibly producing variable and inconsistent outcomes with regards to cell viability, often in the same cell lines (models, methodology and outcomes are summarized in Table 1). The gene discussed is NUDT1; the disease is cancer.