HNRNPK and leukemia: By employing a newly developed 5-ethynyluridine (EU) clicking chemistry technology37 and STED confocal microscopy, we demonstrated co-localization of hnRNPK and active RNA pol-II (CTD-S2P) at nascent RNA, and the co-localization was markedly increased in the 5-AZA-resistant M2AR cells compared to the 5-AZA-sensitive OCI-M2 leukaemia cells (Fig. 5c).