To investigate whether post-translational mechanisms are involved in PVR and Nectin2 expression in MM cells, we initially evaluated surface and total (surface plus intracellular) protein levels by immunofluorescence and FACS analysis on malignant PCs derived from MM patients at different clinical stages (Supplementary Table 1) before and after cell permeabilization, respectively. Here, NECTIN2 is linked to Miyoshi myopathy.