SUMO1 and Miyoshi myopathy: To formally demonstrate that PVR is directly SUMOylated in MM cells, we exploited the approach of Proximity Ligation Assay (PLA) that allows in situ detection of protein interactions and modifications with high specificity and sensitivity; ARK cells were incubated with anti-SUMO1 alone (as negative control) or in combination with anti-PVR, processed following PLA protocol, and analysed by confocal microscopy.