PPIC and cancer: The enrichment of the CTC fraction using OncoQuick® (Greiner Bio-One GmbH, Frickenhausen, Germany), a centrifugation-based separation system, was followed by RT-PCR for six genes upregulated in cancers (cyclin E2, Holliday junction recognition protein, epithelial membrane protein 2, Myelin And Lymphocyte Protein 2 (MAL2), Peptidylprolyl Isomerase C (PPIC), and solute carrier family 6 member 8).