HLA-G and neuroblastoma: To rule out the possibility that this finding was due to inefficient immune magnetic separation leading to contamination with resident BM cells, they performed a flow cytometry analysis of unprocessed BM aspirates, which confirmed that freshly isolated BM-infiltrating NB cells always express two molecules on their cell surface, namely the HLA-G molecule and calprotectin, an heterodimer encoded by the S100A8/A9 genes [15].