RNA was isolated from tissues using the Ambion RNAwiz reagent following the supplier's protocol (1 ml of RNAwiz per 100 mg of tissue). Reverse transcription of RNA was done with MLV RNAse(-) reverse transcriptase (Promega) following the suppliers recommendations. 2 mg of total RNA was used as template for the cDNA synthesis reaction. A one in 10 dilution of the reaction was subsequently used as template for quantitative PCR (Applied Biosystems 7500 Fast System).