To assess the effects of ectopic ADAMTS9 expression on proliferation of breast carcinoma cells, the expression vector incorporating full‐length ADAMTS9 was transfected into breast tumour cell lines, BT549 and SK‐BR‐3, and selected with Hygromycin B for 14 days to construct cell lines stably expressing ADAMTS9. Cells transfected with the empty vector pCEP4 were used as a control. Here, ADAMTS9 is linked to breast carcinoma.