In order to visualize different forms of IGF-1R in prostate cancer cells, we immunoprecipitated IGF-1R from cells stimulated with R1881 for 48 hours and probed the membrane with an antibody against IGF-1Rβ, and observed both a long form representing pro-receptor and also a band representing the IGF-1Rβ subunit (Fig. 4D). Here, IGF1R is linked to prostate carcinoma.