DANCR was sufficient to promote in vitro viability, migration, and invasion, and in vivo xenograft growth of normal breast epithelial cells or breast cancer cells of low malignancy. DANCR was overexpressed in MCF10A and MCF‐7 cells; parental (control) or vector‐transfected cells (vector) were examined in parallel. (A) RT‐qPCR showed elevation of DANCR level in shDANCR cells. (B,C) MTT assay showed that DANCR significantly boosted the viability of indicated cells. Transwell migration (D,E) and invasion (F,G) assay showed that DANCR stimulated the migration and invasion of indicated cells. Representative images of migrated (D) or invaded (F) cells are shown on the left and the quantification on the right (E,G). (H,K) Xenograft tumors (n = 5/group) were generated from vector or DANCR cells. (H,J) Photographs for xenografts from indicated groups. (I,K) The growth curve of xenografts from indicated groups. n = 3, data were shown as mean ± SD. Student’s t‐test was used to determine statistical significance: *P < 0.05, **P < 0.01.