A pioneering study using PC‐9 lung cancer cell lines treated with erlotinib revealed a small fraction of viable quiescent cells that survived drug treatment for 9 days, referred to as DTP, that resumed proliferation in continuous drug exposure for 33 days, referred to as DTEP.[8] In this study, we showed that no additional mutations occurred on AR mRNA in cells treated with inhibitors and that these cells do resist drugs and were phenotypically reversible. The gene discussed is AR; the disease is lung cancer.