BCR and hypophosphatemia: Serum electrolyte changes, such as hypophosphatemia, are common after HSCT [57,58], however, ion concentrations typically return to normal in about 20 days [59], suggesting that the up-regulation of the “ion homeostasis” element observed in our study 6 months after HSCT (Figure 3) cannot be explained by the increased expression of proteins that control serum ion levels, but rather by activation of immune response pathways that involve multiple proteins responsible for the regulation of cellular ion concentrations (especially Ca2+) as it is, for example, in BCR signaling [60].