library_construction_protocol: RNAdvance Cell v2 kit. 50,000 cells were lysed using the lysis buffer from the kit and mixed with 2 µl of 1:100 diluted ERCC RNA spike-in mix 1 Illumina TruSeq Stranded mRNA kit according to the manufacturer's instructions, except one-third of all reaction volumes were used and the final amplification used 13 cycles of PCR.