PPIB and acute lymphoblastic leukemia: In an international collaborative study of B‐ALL, we reported that IKZF1 N159Y is a newly identified rare subtype of B‐ALL with unique gene expression profile, characterised by significant upregulation of the transcriptional coactivator YAP1, SALL1 and ARHGEF28B, and downregulation of the B‐cell receptor signalling and JAK‐STAT signalling pathways.24