Quantitative Real-time PCR (qRT-PCR) relative gene expression for collagen type 2, Aggrecan, Link Protein and the CD44 receptor expressed by bovine NP cells. The expression of each gene represented is expressed relative to basal (untreated) conditions and is normalized to the constitutively expressed gene HPRT. Reading each graph from left to right is the relative fold gene expression of NP cells treated with IL-1β (grey bar), IL-1β + FasL (black bar), cells treated with IL-β + FasL + NCCM (white bar). NCCM was developed from the NPs from six dogs, the NP cells from the NPs of five to six bovine caudal discs cells pooled together. All qRT-PCR experiments were repeated in quadruplicate and are presented with standard error calculations performed for all conditions (statistical significance is P < .05). Abbreviations: qRT-PCR (quantitative Real-Time Polymerase Chain Reaction), CD44 (cell surface glycoprotein cluster of differentiation 44), HPRT (Hypoxanthine-guanine phosphoribosyltransferase), NP cells (nucleus pulposus cells), IL-1β (Interleukin 1 beta), FasL (Fas Ligand), NCCM (notochordal cell conditioned medium).