The IHC and ISH results for 40 BC tissues from the same tumour tissue microarray revealed that the level of hsa_circ_0007990 was correlated with the YBX1 protein (P = 0.027) and E2F1 mRNA (P = 0.038) levels, respectively (Supplementary Fig. S9). The gene discussed is YBX1; the disease is breast cancer.