DNAM-1 and NKG2D ligands are up-regulated on patient-derived PCs after therapeutic treatment. Mononuclear cells were cultured with melphalan (20 μM) or bortezomib (5 nM) in complete medium supplemented with 20 ng/mL IL-3 and 2 ng/mL IL-6. Upon 48-hour treatment, the expression of ULBP1 (1), ULBP2 (2), ULBP3 (3), MICA (A), MICB (B), PVR (P), and Nec-2 (N) was analyzed by flow cytometry gating on CD38⁺CD138⁺ PCs. Three examples of the typical FACS analysis performed are represented in the squares. * = P1; ** = P2. Data are expressed as fold increase between the MFI of specific ligand subtracted for MFI of isotype control of treated cells divided by MFI of specific ligand subtracted for MFI of isotype control of untreated cells.