ESR1 and urinary bladder cancer: Through interrogating the gene–gene interactions in the malignant cell-specific networks and cell–cell interactions between malignant cells and other cells, we identified several other genes may affect the MDK-LRP1-mediated intercellular crosstalk, such as ERBB2, ERBB3, HRAS, and ESR1. The ERBB pathway mutations have been shown to upregulate MDK expression in bladder cancer in previous studies.