As expected, the network of genes correlated with ACVRL1 expression paralleled a similar pattern in the The Cancer Genome Atlas (TCGA) Breast Invasive Carcinoma cohort (24, 25), with a highly significant enrichment for angiogenesis and hypoxia, in keeping with the reported endothelial expression of ALK1 (Supplemental Table 1; supplemental material available online with this article; https://doi.org/10.1172/JCI183086DS1). This evidence concerns the gene ALK and invasive breast carcinoma.