library_construction_protocol: RNA was harvested using RLT buffer (Qiagen) containing 1% 2-mercaptoethanol, followed by RNA reverse transcription by SMART-Seq v4 Ultra Low Input RNA Kit for Sequencing (Clontech). After enzymatic fragmentation of cDNA samples by KAPA Frag kit (KAPA Biosystems), sequencing libraries were prepared using KAPA Hyper Prep Kit (KAPA Biosystems).