Synthetic peptide of SHP-1-C binds to p32/p30 from D/V and D/C cells but has no marked effect on SHP-1 PTPase activity in vitro. (A) Total cell lysates (TCL) from D/V and D/C cells were incubated in binding assays with a synthetic peptide of SHP-1C conjugated to Affi-gel 10. TCL (lanes 1 and 2) and cellular proteins associated with peptide (lanes 3 and 4) were analyzed by SDS-PAGE and Western blotting with antibodies as indicated. The positions of phosphotyrosine proteins and protein size markers are indicated. (B) The PTPase activity of a GST-SHP-1 fusion protein was determined in the absence or presence of the synthetic SHP-1-C peptide (20 to 40 μmol/L). The data represent the mean ± SD values of duplicated samples.