PSMA6 and lung carcinoma: Three other drugs (SJ‐172550 for MDM4, nutlin‐3 for MDM2/MDM4, and carfilzomib for PSMA6 and PSMB6) showed improved IC50 values when used as a monotherapy but increased efficacy when used in combination with erlotinib on NCI‐H820 lung cancer cell lines (Fig. 3B).