Fig. 2From: Expression of the RANK/RANKL/OPG system in the human intervertebral disc: implication for the pathogenesis of intervertebral disc degenerationDetection of basal mRNA expressions of receptor activator of nuclear factor kappa B (RANK)/ RANK ligand (RANKL)/ osteoprotegerin (OPG) in annulus fibrosus (AF), and nucleus pulposus (NP) cells. The mRNA expressions of RANK (a), RANKL (b), and OPG (c) were quantified by real-time polymerase chain reaction. Their expressions in NP cells were normalized by those in AF cells. Significantly higher mRNA expression levels of RANKL and OPG were found in NP cells than those in AF cell; *p < 0.05, **p < 0.01. There was no significant difference in the expression level of RANK between AF and NP cells. The ratio of RANKL/OPG (d) in NP cells had a tendency to be higher compared to that in AF cellsBack to article page