library_construction_protocol: Sorting of cells directly into RLT-buffer and RNA extraction by RNeasy Micro Kit (Qiagen). Library generation:   0.67ng  of total RNA were used for library preparation with the 'SMARTer Stranded Total RNA-Seq Kit v3 – Pico Input Mammalian – 96 Rxns' (#634487; Takara Bio USA, Inc.) according to conditions recommended in user manual #120720. Generated libraries were barcoded by dual indexing approach and were finally amplified with 13 cycles of pcr. Fragment length distribution of generated libraries was monitored using 'Bioanalyzer High Sensitivity DNA Assay' (5067-4626; Agilent Technologies). Quantification of libraries was performed by use of the 'Qubit® dsDNA HS Assay Kit' (Q32854; ThermoFisher Scientific).    Sequencing run:   Equal molar amounts of ten libraries were pooled for a common sequencing run. Accordingly, each analyzed library constitutes 10% of overall flowcell capacity. The library pool was denatured with NaOH and was finally diluted to 1.3pM. 1.3 ml of denatured pool was loaded on an Illumina NextSeq 550 sequencer using a High Output Flowcell for single reads (20024906; Illumina). Sequencing was performed with the following settings: Sequence reads 1 and 2 with 38 bases each; Index reads 1 and 2 with 8 bases each.