RNA was harvested using RNeasy Mini Kit (Qiagen). 1 ug of total RNA was used for the construction of sequencing libraries. Poly(A)+ mRNA from total RNA of one million sorted pro-B cells of WT, TCF3::PBX1 positive-ALL and TCF3::HLF positive-ALL mice or IL1B-sufficient and deficient YCUB2 cells was isolated by NEBNext Poly(A) mRNA Magnetic Isolation Module (New England Biolabs). The library was then prepared by NEBNext Ultra RNA Library Prep Kit for Illumina (New England Biolabs).