ITGA5 and acquired polycythemia vera: The immunophenotypic analysis revealed that BM-MSC from both PV patients and HD highly expressed the cell surface markers CD90, CD73, CD105, CD13, CD29, CD44, CD166 and CD49e, intermediately expressed CD54, and weakly expressed HLA-DR, CD31, CD34, CD14, and CD45 (Figure 1B).