In vitro studies herein illustrate the physiological relevance of elevated stromal Nox4 in PCa and demonstrate its role as a central mediator of (i) reciprocal epithelial‐stromal cell crosstalk, (ii) fibroblast activation and (iii) stromal‐driven tumor (cell)‐promoting hallmarks (summarized in Fig. 6d). This evidence concerns the gene NOX4 and neoplasm.