Tyrosine phosphorylation of MAP kinases in TF-1 cells. TF-1 cells in suspension culture (lanes 1 and 2) or plated on fibronectin-coated wells (lanes 3 and 4) were incubated for 10 minutes at 37°C. Cells in suspension were subsequently treated with (lane 1) or without (lane 2) SLF (10 ng/mL) for 10 minutes at 37°C, then lysed in lysis buffer. Fibronectin-coated wells were washed and the medium without (lane 3) or with (lane 4) SLF (10 ng/mL) was added to the wells. The wells were further incubated for 10 minutes at 37°C and the cells were then lysed in lysis buffer. Equal amounts of protein were immunoprecipitated with agarose-conjugated-anti-p-Tyr MoAb. Immunoprecipitates were separated by 8% SDS-PAGE and subjected to immunoblotting with antipan MAP kinase MoAb. This is a representative result from three separate experiments.