Physical interactions between ObR and HER2. (A) Growing subconfluent cultures of MCF-7 cells were processed for HER2 (red staining) and ObR (green staining) immuofuorescence as described in Materials and Methods. Colocalization of HER2 and ObR was detected by merging (HER2+ObR) images (yellow staining). Cell nuclei were detected by DAPI (blue staining). (B) Total proteins from growing MCF-7 cells were immunoprecipitated with ObR Abs or control unrelated IgG, as described in Materials and Methods. The presence of HER2 in ObR and IgG IPs was detected by WB and is indicated by arrow. 35 μg of total MCF-7 cell proteins were run on the same gel to control HER2 Ab specificity.