As displayed in Fig. 1D, E, linear IRAK3 mRNA was observably digested by RNase R treatment, while circ_IRAK3 was resistant to RNase R. Nuclear-cytoplasmic fractionation assays showed that circIRAK3 was more localized in the cytoplasm of BC cells (Fig. 1F, G). Here, IRAK3 is linked to breast cancer.