Figure 2. Downregulation of miR-155-5p enhances the anti-proliferative effect of cetuximab in TNBC cells. (A) EGFR-overexpressed MDA-MB-231 and (B) MDA-MB-468 cells were transfected with miR-155-5p for 72 h. RT-qPCR was used to detect the level of miR-155-5p in cells. (C) EGFR-overexpressed MDA-MB-231 and (D) MDA-MB-468 cells were treated with cetuximab (0, 5, 10, 20, or 40 nM) and/or the miR-155-5p antagomir (10 nM) for 72 h. The Cell Counting Kit-8 (CCK-8) assay was used to detect cell viability. (E) EGFR-overexpressed MDA-MB-231 and (F) MDA-MB-468 cells were treated with cetuximab (10 nM) and/or the miR-155-5p antagomir (10 nM) for 72 h. Relative fluorescence expression levels were quantified by Ki67 and DAPI staining. **P < 0.01 compared with the control group. ##P < 0.01 compared with the cetuximab 10 nM group.