SMAD1 and breast cancer: As ascertained by ChIP-seq data of human endothelial cells, stimulation with the high-affinity ligand BMP9 produced a strong binding peak of SMAD1 in the promoter region of CLEC14A. To confirm this type of regulation, dual RNAscope-ISH on human breast cancer samples unveiled that expression of ACVRL1 is required for the concurrent detection of CLEC14A in the same cell.