CAV1 and breast cancer: Evidence for functional roles for non-caveolar Cav1 domains came from studies of variants of Mgat5-null murine mammary tumor cells, which express low levels of Cav1 but form neither caveolae nor high molecular mass Cav1 complexes; non-caveolar Cav1 was shown to restrict diffusion of cholera toxin B subunit and EGFR in the plasma membrane and inhibit EGF signaling [29].