What is a biomarker?
A biomarker is a measurable characteristic (i.e. gene expression or protein levels) that can be used to indicate a physiological state.

Tissue Health: Phenotypic markers: aggrecan, type II collagen
Inflammation: Mediators: cytokines, chemokines, & Prostaglandins, leukotrienes
Tissue Catabolism: Degradative enzymes: metalloproteinases, aggrecanase, collagenase
Enzyme Inhibitors: Tissue inhibitor of metalloproteinase (TIMP)
Anti-oxidant activities: Superoxide dismutase (SOD), glutathione peroxidase, catalase
Immune response: Interleukins & Macrophage activity, Natural Killer cell activity
Cellular Detoxification: Phase II Enzymes: NQO1, HMOX1, UGT1A1 & Viability, growth and differentiation