“… 66 Its downstream signaling is mediated by Twist1, which activates the expression of gene programs that may lead to PLK1 inhibitor resistance via EMT and activates the transcriptional regulation of ABCB1 , which encodes the multidrug resistance protein MDR1, also known as P-glycoprotein (P-gp). Solanes-Casado et al 67 further confirmed the EMT process in drug-resistant colorectal cancer cells is driven by AXL signaling and Twist1 as part of their acquired drug resistance mechanism by assessing the expression levels of Ax1 , Twist1 , E-calmodulin , vimentin , ABCB1 , and MDR1 in colorectal cancer cell lines that are PLK inhibitor BI2536-resistant and parental cell lines without detectable mutations in HT29, SW837, and HCT116. In addition, Solanes-Casado et al 67 found that mdr1 expression was significantly higher in BI2536-resistant cell lines than in parental cell lines at both the mRNA and protein levels.…”