CAV1 and breast cancer: Is the decrease in Cav-1, caused by oxygen radicals from the tumor epithelium, mechanistically involved in creating a stroma with low Cav-1 CAFs that promote tumor cell aggressiveness by providing metabolites, as suggested for breast cancer by Lissanti and coworkers [36], or is it a marker for other changes more directly associated with tumor aggressiveness such as tumor hypoxia (hypoxia is reported to decrease Cav-1 in CAFs, 38)?