PDE5 inhibitors also improved the chemosensitivity of anti-cancer agents by increasing endocytosis-mediated cellular drug uptake in lung cancer cells; for instance, oral administration of the PDE5 inhibitor vardenafil significantly increases the accumulation and enhances the anti-tumor effect of trastuzumab in a xenograft mouse model of lung cancer [207]. Here, PDE5A is linked to neoplasm.