Fig. 8.

Graphical illustration of the results. Our data suggest that the loss of activating enhancer binding protein 2 epsilon (AP-2ε) results in an enhanced basal matrix metalloproteinase 13 (Mmp13) expression level in articular chondrocytes of Tfap2e ^−/− mice as compared with wild-type (WT) mice. After osteoarthritis (OA) onset, expression of Mmp13 is induced in both genotypes by a comparable amount (3.2-fold in WT mice and 2.4-fold in Tfap2e ^−/− mice), which is most likely due to the effect of other OA-associated transcription factors. However, because of the higher basal expression level, a similar induction rate leads to a significantly higher Mmp13 expression level in chondrocytes of Tfap2e ^−/− mice compared with WT mice 17 days after OA surgery. Tfap2e ^−/−, Deficient for activating enhancer binding protein 2, epsilon