ABCB1 and neoplasm: This includes mutations of TUB, selection of tubulin isotypes and its post-translational modifications [18,48], an increased efflux of MTAs due to the upregulation of the MDR1 gene [49], etc. Thus, a broad toxicity profile of MTAs and the rapidly developing resistance remain the main driving forces to develop the novel therapeutic agents effectively targeting microtubules and exhibiting potent anti-tumor activities.