After 6 weeks of treatment, mRNA from the condylar fibrocartilage of six mice from each group was extracted to determine changes in response to DOL or DOL + RL. Total RNA from the mandibular condylar fibrocartilage was extracted using TRIzol Reagent (Ambion by Life Technologies), purified using the DNase treatment and removal kit (Ambion by Life Technologies), and converted to cDNA utilizing a High Capacity cDNA Reverse Transcription Kit (Applied Biosystems). Both the left and right mandibular condylar fibrocartilage was pooled together for each sample. For quantification of gene expression, real-time polymerase chain reaction (RT-PCR) was conducted to assess the relative levels of genes of interest using the ViiA 7 Real-Time PCR System (Applied Biosystems) following the protocol detailed in Chen et al.34 (link) Expression of each gene of interest was determined relative to the Gapdh housekeeping gene (Gapdh – MM99999915_g1) utilizing the ΔΔCT method. Gene expression was performed for the following chondrocyte markers: parathyroid hormone-related protein (Pthrp-Mm00436057_m1); SRY-box containing gene 9 (Sox9-MM00448840_m1); collagen type II (Col2a1-Mm00491889_m1); indian hedgehog (Ihh-Mm00439613_m1); and collagen type X (Col10a1-Mm00487041_m1).