Colocalization of IRS-1 and Bcl-2. A part of IRS-1 colocalizes with Bcl-2, and insulin stimulation of cells does not affect localization of IRS-1 and Bcl-2. CHO-IR/IRS-1/Bcl-2 cells were treated with (D–F) or without (A–C) insulin (100 nM) at 37°C for 10 min. Then cells were fixed and incubated with anti-IRS-1 antibody (C-20; A, B, D, and E) and anti-Bcl-2 antibody (clone 124; B, C, E, and F), followed by FITC-conjugated antirabbit (for C-20) or Texas Red-conjugated anti-mouse (for anti-Bcl-2 antibody) secondary antibodies.