IFN-β downregulates IL-6–induced PTP1D/Syp tyrosine phosphorylation and association with gp130. PTP1D/Syp was immunoprecipitated from lysates of IFN-β and IL-6–treated U266 cells (1 × 10⁷) followed by immunoblotting with both anti-pTyr (top panel) and anti-PTP1D/Syp (middle panel) specific MoAbs. The lower panel shows samples (1.5 × 10⁷ cells) immunoprecipitated with gp130 followed by probing with anti-PTP1D/Syp specific MoAb. Arrow indicates the position of PTP1D/Syp.