This study found that an increase in copy number of GATA3 and PPARG was independently associated with higher ERBB2 expression in patient samples of urothelial carcinoma, providing a potential explanation for HER2 overexpression in tumors without ERBB2 amplification and a way to identify these tumors for HER2-targeted therapies. This evidence concerns the gene GATA3 and urothelial carcinoma.