miR-153 negatively regulates RUNX2 expression in SK-BR-3 and BT-549 cells. miR-153 mimic and scramble miR mimic were transiently transfected into SK-BR-3 and BT-549 cells, respectively. (A) The mRNA expression level of RUNX2 in SK-BR-3 and BT-549 cells was detected by RT-qPCR. (B) The protein expression level of RUNX2 in SK-BR-3 and BT-549 cells was determined by western blotting. **P<0.01 vs. miR-NC. miR-153 inhibitor and NC inhibitor were transiently transfected into SK-BR-3 and BT-549 cells, respectively. The mRNA expression level of (C) miR-153 and (D) RUNX2 in SK-BR-3 and BT-549 cells was detected by RT-qPCR. (E) The protein expression level of RUNX2 in SK-BR-3 and BT-549 cells was determined by western blotting. **P<0.01 vs. NC inhibitor. RUNX2, runt-related transcription factor 2; SK-BR-3 and BT-549, human breast cancer cell lines; miR, microRNA; miR-NC, breast cancer cell lines SK-BR-3 and BT-549 transfected with scramble miR; miR-153, breast cancer cell lines SK-BR-3 and BT-549 transfected with miR-153 mimic; NC inhibitor, breast cancer cell lines SK-BR-3 and BT-549 transfected with miRNA NC inhibitor; miR-153 inhibitor, breast cancer cell lines SK-BR-3 and BT-549 transfected with miR-153 inhibitor; RT-qPCR, reverse transcription-quantitative polymerase chain reaction.