Sun et al (2019) showed that circMYBL2 facilitated the binding of PTBP1 to FLT3 mRNA, enhanced FLT3 translation of FL, and promoted leukemia progression (Sun et al, 2019). Wang et al (2019) reported that circFOXP1, through the interaction with PTPB1, stabilized PKLR mRNA (Wang et al, 2019). Here, we added the new finding that circEXOC5-PTBP1 interaction accelerated the decay of Skp2 mRNA, which then indirectly protected Runx2 from ubiquitin-mediated degradation. This evidence concerns the gene RUNX2 and leukemia.