Besides Lgr5+ cells, Klf-4 (Kruppel-like factor 4) disruption or PPARD (peroxisome proliferator-activated receptor delta) overexpression in Villin promoter-expressing stem cells spontaneously result in gastric carcinogenesis (Li et al., 2012; Zuo et al., 2019), CCK2R+ cells potentially explains the gastrin-mediated effects on gastric cancer progression (Hayakawa et al., 2015b). The gene discussed is PPARD; the disease is gastric cancer.