mTOR inhibitors (Fig. 1), while previously unsuccessful in a 2018 study in KRAS-mutant cancers (NCT01347866) (Table 1), have been seen to promote tumour regression in the treatment of KRASG12C inhibitor refractory disease [41], and may yet prove effective by using STK11-mutation status as a surrogate biomarker for pathway activity. The gene discussed is KRAS; the disease is cancer.