In line with known drug pharmacology and disease biology, the tolvaptan-ADPKD diffusion profile identifies V2R as the sole drug target for tolvaptan, and also identifies key proteins known to be perturbed in the ADPKD disease state, including V2R itself, as well as polycystin-2, angiotensinogen, cystic fibrosis transmembrane conductance regulator (CFTR) and epidermal growth factor (EGFR). The gene discussed is EGF; the disease is autosomal dominant polycystic kidney disease.