['To study effect of AG490 on the activation, proliferation, cell cycle, apoptosis and the expression of protein ICBP90 of Jurkat T cells. To explore the possibility of inhibiting and the initial growth mechanism of Jurkat T cells by blocking JAK signaling pathway.', 'The expression level of CD69 and CD25 on the surface of Jurkat T cells was evaluated by fluorescin-conjugated monoclonal antibody double labeling technique. The proliferation of Jurkat T cells was analyzed by MTT method. The cycle of Jurkat T cell was analyzed by PI staining and Flow Cytometry. The apoptosis of Jurkat T cells was analyzed by Annexin V-FITC and PI staining. The expression of ICBP90 that correlated with the cell proliferation was checked by Western blot.', 'The results came out that the proliferation capacity of Jurkat T cells was decreased with the increasing of AG490 ranging from 1 mmol/L to 30 mmol/L in a dose-dependent manner with the highest inhibitory rate of 27.37%. Cell-cycle analysis revealed that AG490 arrest it in G0/G1 phase and inhibited its entrance into S and G2/M phase, and reduced the expression of protein ICBP90, especially in the 24 h treatment. But the apoptosis of Jurkat T cells was not promoted by AG490.'] Does [ Inhibitor of tyrosine phosphorylation AG490 inhibit the proliferation of Jurkat T cells ]?