Human materials were obtained from Johns Hopkins Hospital and the Netherlands Cancer Institute. Expression of HOX transcripts was determined using ultra-high density HOX tiling arrays7 (link) and qRT-PCR. Kaplan-Meier analyses of breast cancer patients were as described13 (link). We used retroviral transduction to overexpress HOTAIR and luciferase, and used siRNA or shRNA to deplete the indicated transcripts. Matrix invasion was measured by the transwell Matrigel assay. We implanted cells in the mammary fat pad of SCID mice, and monitored primary tumor growth and lung metastasis by bioluminescence. Cells were injected into the tail vein of nude mice, and lungs were analyzed at 9 weeks to quantify lung colonization in vivo. ChIP-chip was performed as described7 (link) using human whole genome promoter tiling arrays (Roche Nimblegen, Wisconsin). Module map and GO enrichment analyses were done using Genomica20 (link).