ACTA1 and carcinoma: Desmoplastic stroma rich in α‐smooth muscle actin (α‐SMA)‐positive myofibroblasts, a hallmark of activated fibroblasts, is frequently observed in various human carcinomas including those of the breast, prostate, pancreas, lung, and colon.1, 2, 3 In contrast, such myofibroblasts are rarely identified within nontumor stromal regions.