MMP2 and breast cancer: Furthermore, miR-1233-3p could downregulate KLF4 (which belongs to the Krüppel family of transcription factors, has a dual function in cancer development, and acts as a tumor suppressor in breast cancer) at the mRNA and protein levels and reduce the MMP2 level indirectly through the circEHMT1/miR-1233-3p/KLF4 axis indirectly through the circEHMT1/miR-1233-3p/KLF4 axis to reduce MMP2 levels.