Total RNA was extracted using the QIAamp RNA Blood Mini Kit (Qiagen) according to the manufacturer's instructions. Contaminating genomic DNA was removed by on-column treatment of each sample with DNase I (Qiagen). Purity, concentration and integrity of total RNA were assessed using two independent techniques. RNA purity and concentration were evaluated by absorbance readings using a NanoDrop ND-1000 spectrophotometer (Thermo Fisher Scientific). RNA quality was determined with an RNA 6000 nano LabChip Kit in the Agilent Bioanalyzer 2100 system. Quality was evaluated using the RNA Integrity Number (RIN) [31] .