TWIST1 and breast cancer: Furthermore, RT-PCR characterization of CTCs isolated from early-stage breast cancer patients, where Twist1 expression was used as an EMT marker, revealed the presence of EMT-CTCs in 31% of patients [93], whereas immunostaining experiments revealed that EMT-CTC expressing Twist1 and vimentin were identified in 73% and 77% of patients with early-stage breast cancer, respectively [57].