Objective      To study the effect of IRF-4 binding protein (IBP) on resistance of salivary adenoid cystic carcinoma (SACC) cells to taxol and its mechanism.       Methods      ACC2 cells transfected with IBP and blank control cells (ACC2-C1 cells) were divided into 5 groups according to their taxol concentration. Effect of IBP on proliferation of SACC cells was detected by MTT assay 72 h after taxol was used. Occurrence of changes in microtubules of SACC cells and its relation with IBP were observed with tubulin immunofluorescence staining before and after taxol was used.       Results      IBP increased the resistance of ACC2 cells to taxol

especially at the concentration of 5 μg/ml. The point-like microtubules of ACC2-C1 cells aggregated into a clump while the microtubules of ACC2-C1/ IBP cells were arranged in disorder and fractured

indicating that IBP can promote depolymerization of microtubules. Green fluorescence of IBP and red fluorescence of microtubules were merged as a yellow color

showing that IBP and microtubules are located at the same site.       Conclusion      IBP promotes resistance of SACC cells to taxol.