CCNE1 and breast cancer: It is reported that circRNAs could function as ceRNAs to sponge miRNAs and regulate cancer progression.11 In triple‐negative breast cancer, circAGFG1 acted as a ceRNA for miR‐195 to regulate cyclin E1 and promote cancer progression.12 And hsa_circ_001783 was reported to promote breast cancer progression via sponging miR‐200c.13 Here, we found that circFBXL5 had binding sites for miR‐660 and could function as a miR‐660 sponge.