Whilst both BPH and CaP expressed EGF (BPH = 195.61 +/- 19.94 ng g-1 protein; CaP = 235.60 +/- 24.45 ng g-1 protein) and TGF alpha (BPH = 92.57 +/- 7.60 ng g-1 protein; CaP = 100.73 +/- 15.47 ng g-1 protein) in equal concentrations, the levels of EGF in any tissue extract were on average twice those of TGF alpha. This evidence concerns the gene EGF and benign prostatic hyperplasia.