ASPG and neoplasm: While cells have higher permeability with Asn than Asp, the activity of asparaginase in bladder cancer cells was insufficient, which could not convert Asn into Asp.93 After using guinea pig asparaginase 1 (gpASNase1) to promote the conversion of Asn to Asp in tumor cells, the growth rate of tumor cells was significantly increased, suggesting that Asp acquisition is an endogenous metabolic limitation in tumors with difficult Asp acquisition.93 It was suggested that Asp is an intrinsic limit to the growth of some tumors in vivo, and breaching this limit will promote tumor growth.