A low number of human fetal bone marrow MSC (fMSC) display surface CXCR4. Three different anti-CXCR4 antibody clones were used 12G5, ab2074 and 4417 as detailed in the methods, with fluorophore labelled secondary antibodies used where necessary. A) CXCR4 surface expression (fluorescence intensity vs. forward scatter) by flow cytometry shown as dot plots. B) After permeabilisation, the majority of cells show intracellular stores of CXCR4. The horizontal gates delineate the position of relevant isotype control antibody. Human adult bone marrow MSC also show low expression of CXCR4 on the cell surface (C) with large intracellular stores of this receptor (D). E) Each of the anti-CXCR4 antibodies are able to detect >80% cells with surface expression of CXCR4 on HeLa cells. F) Both the anti-CXCR4 antibodies 12G5 and ab2074 are able to detect >80% cells with surface expression of CXCR4 on THP-1 human monocytic leukemia cells.