Previously, we have demonstrated that hSef expression is closely linked with tumor aggressiveness, with reduced expression being a feature of high‐grade and metastatic clinical prostate cancer.13 To corroborate this finding in vivo, a xenograft model was adapted from a previously reported protocol for prostate cancer lung metastasis using PC3M.18 This cell line is known to have very low levels of endogenous hSef.17 PC3M‐EV and PC3M‐Sef cells were used to produce lateral thoracic wall tumors in immune‐deficient mice (Fig. 1a). The gene discussed is IL17RD; the disease is prostate cancer.