design: Total RNA was extracted from each cell line using an RNeasy Mini Kit (Qiagen, Hilden, Germany). After a quality control step with a 2100 bioanalyzer (Agilent Technologies, Santa Clara, CA), the library was constructed using a TruSeq Stranded mRNA Prep kit (Illumina, San Diego, CA) according to the manufacturerfs instructions and subjected to sequencing using an HiSeq2000 sequencer.