In this context, it seems likely that RNPs either released from infecting virions or assembled at the beginning of the infection process might be preferentially devoted to mRNA synthesis rather than to virus assembly. This hypothesis is consistent with CLSM data presented here showing that early after infection the three RNP components merge within discrete granules largely devoid of the VP2 polypeptide. Research into biological markers hopes to provide the clinician with an opportunity to choose the best treatment for the individual patient. Several clinical and laboratory values give prognostic information regarding treatment strategy for patients with metastatic colorectal cancer. KRAS status is presently the only biomarker routinely used to select patients with mCRC for epidermal growth factor receptor inhibition-targeted therapy. Patients with wild type KRAS mCRC benefit from inhibition in combination with FOLFIRI or FOLFOX, even though the effect is not confirmed in all phase III studies, where EGFR-inhibitors were combined with some oxaliplatin-based regimes. In the NORDIC VII study, a survival benefit of adding cetuximab to the Nordic FLOX regimen could not be confirmed. Identification of new predictive and prognostic biomarkers is essential. YKL-40 is a highly conserved glycoprotein, and its gene is located on chromosome 1q32.1. The YKL-40 protein is highly expressed in embryonic tissue characterized by rapid proliferation and differentitation. In adults, high YKL-40 expression is observed in cells with high cellular activity. YKL-40 is produced by cancer cells, macrophages, and neutrophils and is stimulated by hypoxia and IL-6. YKL-40 also induces cancer angiogenesis both independently and MLN4924 through stimulating vascular endothelial growth factor. Furthermore YKL-40 upregulates pro-inflammatory mediators and activates the Akt signaling pathway in colonic epithelial cells. Recently, it has beed demonstrated that YKL-40 regulates cellular and tissue responses via the IL-13 receptor a2 and it activates macrophage mitogen-activated protein kinase, protein kinase B/AKT, and Wnt/b-catenin signaling. YKL-40 is known to be an independent prognostic biomarker of short overall survival in patients with different types of cancers and in patients with CRC after surgery. Little is known about the prognostic value of YKL-40 in patients with mCRC. Furthermore, high plasma YKL-40 in subjects from the general population is associated with an increased risk of developing gastrointestinal cancer and death from gastrointestinal cancer. EGFR mediates stimulation of cellular proliferation, survival, and motility and is involved in tumorigenesis if abnormally activated. Alterations within the EGFR signaling cascade like gene mutations, gene amplifications, and protein overexpression play a role in colorectal carcinogenesis. EGFR is an established target for cancer treatment, and inhibition of the receptor has shown clinical efficacy in patients with mCRC. In the present study, we tested the hypothesis that an elevated plasma concentration of YKL-40 is associated with short PFS and OS in patients.