Informative surface markers expressed by MSCs. Phenotypic analysis of MSCs derived from a representative donor (donor 2). (A) Expression of typical markers of MSCs. (B) Expression profiles of known ligands for activating NK receptors. Results are expressed as MFI in arbitrary units (x-axis) compared with number of cells (y-axis). Open histograms represent controls using the second reagent only. Similar data were obtained in 15 different donors.