A: Immunoblotting of IGF-1R, pho-IGF-1R and pho-IRS-1 in proliferating BPH-1 cells treated with various doses of metformin for 24 hours, or with 5 mM metformin for the indicated times. B-C: Quantification of the immunoblot protein expression of pho-IGF-1R (B) and pho-IRS-1 (C) in BPH-1 cells treated with 5 mM Metformin for 24 hours, and normalized to IGF-1R or GAPDH, respectively. **, P<0.001 compared with control group. D-E: Representative immunofluorescence images of pho-IGF-1R in BPH-1 (D) and P69 (E) cells after exposure to 100 ng/mL IGF-1 in the presence or absence of 5 mM metformin for 48 hours. F-G: Immunoblotting of pho-IGF-1R and pho-IRS-1 in BPH-1 (F) and P69 (G) cells 48 hours after treatment of IGF-1(100 ng/mL) and metformin (5 mM). CTR: untreated control, Met: metformin.