EFNA1 and cancer: These results, in conjunction with the observation that Erk inhibition by the MEK inhibitor U0126 abolished the pro-proliferative effect of the CM (Fig. 6g), lead us to propose that sEV-associated EphA2 promotes the proliferation of ephrin-A1-expressing cancer cells by activating the Erk pathway through EphA2/ephrin-A1 reverse signalling.