BEX4 and cancer: In addition, acetylation of α-TUB is frequently elevated in many human cancers,20 and hyperacetylation of α-TUB interrupts the normal timing of mitotic progression and confers resistance to microtubule inhibitors.9, 21 To test the possibility that BEX4 formed complexes with microtubule subunits and regulated their modification, lysates of HeLa cells stably expressing tandem affinity purification (TAP)-tagged BEX4 or TAP alone were incubated with the streptavidin beads and analyzed by immunoblotting.