In contrast, Meflin/Islr-positive fibroblasts proliferate in the cancer stroma (Mizutani et al., 2019; Kobayashi et al., 2021) and in cardiac and lung fibrosis (Hara et al., 2019; Nakahara et al., 2021) under pathological conditions. The gene discussed is ISLR; the disease is pulmonary fibrosis.