Using a microfluidic CTC capture device, the TMPRSS2-ERG fusion, the TKIs sensitizing EGFR activating mutations and the EGFR T790M TKI-resistance mutation were detected in CTCs from patients with prostate and lung cancer metastatic disease respectively, whereas mutations of the AR, KRAS and BRAF genes have been identified in CTC-enriched samples isolated from prostate and mCRC patients, respectively, using the CellSearch Profile Kit [24], [37], [38], [39]. The gene discussed is KRAS; the disease is lung cancer.