Those expressed extracellularly and with an average expression level at least three-fold greater in BPH RNA pools than in the prostate cancer RNA pools included: CDH13, CHRNB1, COL4A5, EFEMP2, EMP3, F10 (16-fold), FGF2, FGFBP1 (10-fold), IGF1, IGF2 (18-fold), LIPG, RARB, SGCA, SGCD, TGFB1, TGFB3 (14-fold), TGFBR2 and TIMP2 of the “high in BPH, moderate in prostate cancer” group; SMOC1 (26-fold) in the “high in BPH, low in prostate cancer” group; and SCGB3A1 (15-fold) and SCGB1A1 (14-fold) in the “moderate in BPH, low in prostate cancer” group. The gene discussed is COL4A5; the disease is benign prostatic hyperplasia.