BEX4 (brain expressed X-linked 4) is a microtubule-associated protein that regulates cellular processes through modulation of tubulin acetylation. The protein localizes to microtubules and spindle poles, where it interacts with α-tubulin and inhibits SIRT2 deacetylase activity, leading to microtubule hyperacetylation 1. This mechanism is crucial for chromosome X and genomic stability, as BEX4 overexpression can induce aneuploidy and resistance to apoptotic cell death 1. BEX4 exhibits context-dependent roles in cancer, functioning as a tumor suppressor in several malignancies including clear cell renal cell carcinoma, oral squamous cell carcinoma, and gastric cancer, where decreased expression correlates with poor prognosis 234. Conversely, BEX4 acts as an oncogene in lung adenocarcinoma and glioblastoma, promoting cell proliferation and radioresistance through YAP/TAZ signaling pathway activation 56. The protein's tumor suppressive effects are mediated through stabilization of SH2D4A by preventing ubiquitination at lysine 69, which requires BEX4-mediated inhibition of SIRT2 activity 2. These findings establish BEX4 as a critical regulator of microtubule dynamics with significant implications for cancer progression and therapeutic targeting.