The formation of blebs in 4TorKO cells is independent of K48-linked Ub. (A) Structure of murine cytomegalovirus tegument protein M48 (red) bound to Ub (green) (PDB ID 2J7Q). (B) Schematic representation of MLF2 fused to M48 followed by a C-terminal Flag tag. The location of the catalytic cysteine residue is highlighted in yellow. (C) Representative confocal images of 4TorKO cells expressing MLF2-M48^WT or a catalytically inactive mutant MLF2-M48^C23. Cells were costained with anti–K48-Ub and anti-Flag antibodies. Scale bar, 10 µm.