GM-CSF induces the association of pp135 with Shc. The lysates from UT-7 cells stimulated with GM-CSF (lanes 1 and 3) or unstimulated (lanes 2 and 4) were mixed with anti-Shc. The resulting precipitates were subjected to SDS-PAGE and immunoblotted with anti-Py (lanes 1 and 2) and reprobed with anti-P6 (lanes 3 and 4). Molecular weight markers, indicated at the left, are given in kilodaltons. The arrow indicates the position of pp135.