S100B and thyrotoxicosis: Furthermore, the net effect of viral proteins (because of viral autoregulation) will fluctuate initially between receptor agonist and antagonist function, before becoming predominantly antagonistic, thus providing a possible explanation for transient thyrotoxicosis during early thyroiditis (before hypothyroidism supervenes), for hypoglycaemia seen during early insulin-receptor antibody-mediated insulin resistance [153], and for the contradictory functions ascribed to HIV nef [154].