Total RNA from tissue samples and cell lines were isolated using TRIzol. To remove residual gDNA contaminants, total RNA samples were DNase I-digested and further purified using the RNA Clean & Concentrator-5 kit (Zymo Research). Libraries for RNA sequencing were prepared by the Genomics and Proteomics Core Facility of the German Cancer Research Center using the Illumina TruSeq Stranded RNA kit.