Reverse transcription and cDNA amplification were carried out using a modified Smart-seq2 protocol (Picelli et al., 2014). Single cells were sorted by FACS as described above into 96-well plates containing 0.1 μl of RNase inhibitor (Clontech, Cat# 2313A), 1.9 μl of 0.2% Triton X-100 (Sigma, Cat# T9284), 1 μl of 10 µM oligo-dT primer (5′-AAGCAGTGGTATCA ACGCAGAGTAC T30VN-3′) and 1 μl of dNTP mix (10 mM each; Fermentas, Cat# R0192) in each well. Plates were either stored at -80 °C or processed immediately. Reverse transcription, PCR preamplification, PCR purification were performed following Picelli's protocol (Picelli et al., 2014). As mRNA quality control, 1 ul of each PCR product was used as template for qPCR detection of mCherry expression and samples with Ct value higher than 30 will be discard. PCR products were purified with 1 × Agencourt Ampure XP beads (Beckman Coulter, Cat# A63881) and the final product was reconstituted in 20 µl TE buffer. The concentration of cDNA was measured by Qubit™