FIG. 3.
Overexpression of WT-, but not a proline mutant, PTP1B in 3Y1-v-crk cells causes dephosphorylation of a 130-kDa protein that comigrates with p130Cas. Lysates derived from representative 3Y1-v-crk stable cell lines expressing vector alone (C; clone 1), WT-PTP1B (clone 10), CS-PTP1B (cysteine to serine, enzymatically inactive; clone 2), and PA-PTP1B (proline-to-alanine mutation, defective in p130Cas SH3 binding; clone 5) were separated by SDS–7% PAGE and immunoblotted with antiphosphotyrosine (anti-PY) antibodies. Numbers at right are molecular masses in kilodaltons. Arrows and forks indicate prominent phosphotyrosyl proteins.