RNA seq data reveals distinct expression of HSPC regulators by different niche cell populations. (A) PCA based on gene expression of the 579 ligands from the receptor-ligand database by niche cells. Dots, individual samples; open squares, barycenters of the different samples for a given cell population. (B) Hierarchical clustering of niche cell samples based on ligand expression. (C) Heatmap shows mean rlog transformed expression values of known HSPC regulators (ligands) in distinct niche cells. (D) Hierarchical clustering of HSPCs based on gene expression of the 555 receptors from the receptor-ligand database.