ACTA2 and neoplasm: Immunofluorescent analysis of the stromal marker protein smooth muscle actin (ACTA2) together with Cav1 further revealed that in PC3(−)-derived tumors some Cav1 expressing epithelial cells can be detected close to fibroblast-enriched tumor regions, which led us speculate that the recruited stromal cells might mediate partially Cav1 re-expression in the prostate epithelial PC3 cells which because of the phenotype of implanted stable transduced PC3(−) cells must be due to a Cav1 substitution (Fig. 3B, arrows).