For example, circEHMT1, which we identified as a risk factor in NSCLC, has been shown in breast cancer studies to inhibit cancer cell metastasis by reducing MMP2 levels through the circEHMT1/miR-1233-3p/KLF4 axis.52 In breast cancer, this mechanism is thought to contribute to a more favorable prognosis by controlling metastatic spread. Here, MMP2 is linked to breast carcinoma.