SP2 and plasma cell myeloma: A major obstacle in cloning functionally rearranged IgG sequences from many mouse hybridomas is the presence of an aberrant kappa IgG light chain transcript expressed by the Sp2/0-Ag14 (Sp2/0) hybridoma (Carroll et al., 1988) that frequently serves as a ‘myeloma’ partner for fusion with mouse splenocytes to generate mAb-producing hybridomas (Shulman et al., 1978), and that was used as the fusion partner in all of our mAb generation efforts (Bekele-Arcuri et al., 1996; Gong et al., 2016).