HIF1A and cancer: More important, as a microtubule destabilizing agent, fenbendazole acts on worms primarily by binding to tubulin and disrupting tubulin-microtubule balance, stabilizes the transcriptional activator HIF-1α, causes cell cycle arrest and mitotic cell death, shows anti-cancer effects against several cancer types [2–4] and exhibits anti-cancer effects in paclitaxel and doxorubicin-resistant cancer cells [5, 6].