KRT19 and non-small cell lung carcinoma: Therefore, in a setting of metastatic NSCLC patients, we tried to optimize a method of enrichment for CTC detection based on negative immunomagnetic selection of CTCs associated with a RT-PCR analysis for the expression of epithelial (CEA and CK19) and EMT-related markers such as vimentin and transcription factors (Snail1 and 2, ZEB1 and 2, and Twist1 and 2).