EGFR and breast cancer: Fig 4A shows that vitrified BRx142 CTCs exhibit no significant deviation in RIN value compared to fresh, unfrozen controls. Based upon the positive results, qPCR was performed to determine whether vitrification had an effect on relative gene expression for the BRx142 CTC cell line. We chose a panel of common breast cancer biomarkers, including EpCAM, Her2, EGFR, Met and Cdh3. Among the selected biomarkers, no significant deviation from control levels was observed (Fig 4B).