CALR and systemic lupus erythematosus: Further evidence linking EBV to SLE is based on studies demonstrating that antibodies to the Epstein Barr virus nuclear antigen 1 (EBNA‐1), the major nuclear protein in EBV which is expressed in all EBV infected cells, cross‐react with the splicesomal ribonucleoproteins, Sm B/B′, Sm D, nRNPs, and Ro.