Previous study reported that PTBP1 could affect the translation of ADAR1 in glioma cells47, which may serve as an additional regulatory mechanism of PTBP1 on circCHEK2. However, we did not observe any obvious reduction in ADAR1 protein level upon silencing of PTBP1 (Supplementary Fig. 3e). Here, PTBP1 is linked to central nervous system cancer.