H2a and H2a mutated in its three glycosylation sites (H2aΔgly), subcloned in pCDNA1, were previously described (Kamhi-Nesher et al., 2001 (link); Groisman et al., 2006 ), as were H2aG78R fused through its C-terminus to H2a-RFP (Kondratyev et al., 2007 (link)), FLAG-tagged Herp (Okuda-Shimizu and Hendershot, 2007 (link)), β1,3-galactosyltransferase (GalT)–yellow fluorescent protein (YFP), and myc-tagged human HRD1 (Groisman et al., 2006 ; Kondratyev et al., 2007 (link); Avezov et al., 2008 (link)). Hemagglutinin (HA)-tagged BACE476 (Bernasconi et al., 2010 (link)) was a kind gift of M. Molinari (IRB, Bellinzona, Switzerland). S-tagged XTP3-B, S-tagged OS-9.1, and OS-9.2 (Christianson et al., 2008 (link)) were previously described (Shenkman et al., 2013 (link)). H2a subcloned using an EcoRI restriction site in MSCVpuro, H2aΔgly subcloned using EcoRI and BamH1 restriction sites in pMIG (Addgene, Cambridge, MA), and pCL-Eco Retrovirus Packaging Vector (Imgenex, San Diego, CA) were used for infections.