Apelin-13 is extensively expressed in various tissues, particularly breast tissue. Apelin‑13 has been shown to promote tumor proliferation in various types of cancer, including hepatocellular, lung and ovarian cancer. However, the effect and molecular mechanism of apelin‑13 in breast cancer cells remains unclear. The present study investigated the effect of apelin‑13 on MCF‑7. Therefore, cell proliferation was determined by MTT and flow cytometry analysis. The results revealed that apelin‑13 markedly increased cell proliferation. Transwell assays demonstrated that apelin‑13 increased MCF‑7 cell invasion. Apelin‑13 also markedly increased the expression of cyclin D1, extracellular matrix metalloproteinase‑1 and amplified in breast cancer 1 (AIB1) in a dose‑dependent manner by polymerase chain reaction assays. To study the molecular mechanism, cell proliferation, invasion and cyclin D1 were inhibited by pre‑treatment with 10 µM of PD98059 (ERK(1/2) inhibitor). Western blotting results suggested that apelin‑13 significantly enhances the expression of p‑ERK(1/2) in a concentration‑dependent manner. In conclusion, the results suggest that apelin‑13 promoted MCF-7 cell proliferation and invasion via the ERK1/2/AIB1 signaling pathway.