Identification of proteins that interact with circMYBL2. (A) Schematic of circMYBL2 linearization and the tRSA RNA pulldown assay. (B) Identification of translation-associated proteins that interact with circMYBL2 by silver staining and MS. (C) Detection of interactions between circMYBL2 and RBPs by western blot analysis. (D-E) RIP of RBPs using anti-IgG or anti-RBP (PTBP1, DHX9, SYNCRIP, or hnRNPA1) antibodies. The percentage of RIP-enriched circMYBL2 and FLT3 mRNA relative to the input value was calculated by qRT-PCR. (F) Western blot showing the augmented decrease in FLT3 kinase expression upon knockdown of both circMYBL2 and PTBP1 in MOLM-13 and MV4-11 cells. (G) Effect of knockdown of both circMYBL2 and PTBP1 on proliferation. (H-I) Western blot showing downregulation of FLT3 protein expression upon PTBP1 knockdown in MOLM-13 and MV4-11 cells and in FLT3-ITD AML patient samples. SA, streptavidin.