ERBB2 and urinary bladder cancer: We also used 5637 cells, an EGFR-amplified bladder cancer cell line expressing both S310F HER2 mutant and wild-type HER2 to analyze the downstream signaling of HER2 mutant and found that the S310F HER2 mutant efficiently formed heterodimers with EGFR, which could not be inhibited by the combination of trastuzumab and pertuzumab.