PPP4C and systemic lupus erythematosus: Table 5 shows that many autoantigens in SLE, including known primary SLE autoantigens, associate with PPP4C. Under this hypothesis, the broad array of autoantigens in SLE is a consequence of the many functions of PPP4C, together with secondary immunogenicity caused by the aberrant clearance of apoptotic cells [52], [81].