Figure 5. Molecular interaction between RPTPσ and Ret.

(A) RPTPσ and Ret expression vectors were cotransfected in HEK293T cells and treated with or without GDNF/GFRα1. Top: Cell lysates were immunoprecipitated with anti-RPTPσ antibodies and resolved by SDS-PAGE, followed by immunoblotting with an anti-Ret antibody. The same membrane was re-blotted with anti-RPTPσ antibody. Ret proteins were specifically co-immunoprecipitated with RPTPσ-WT and RPTPσ-D/A. Bottom: Total cell lysates were immunoblotted with the indicated antibodies. Phosphorylation levels of Ret and its downstream signaling components were significantly reduced when Ret was cotransfected with RPTPσ-WT or RPTPσ-D/A. (B) Flow cytometric analysis of annexin V–PE staining. Cells were sorted for GFP-positive signaling. The percentage of annexin V–PE–positive cells was increased in RPTPσ-WT. This effect was suppressed by Ret coexpression. The results shown are means ± SD from 3 independent experiments.