GFAP and neuroblastoma: Using the marker of astrocytic activation, we found that the expression of GFAP was not significantly changed in cerebral cortical astrocytes (Fig. 3a, c) and cerebellar astrocytes (Fig. 3b, d) incubated with sera or IgG from the OMS + NB group compared with those from the NB group and healthy control group at least under our experimental conditions, suggesting that the enhancement of activation induced by IgG from children with OMS and NB is specific to microglias, but not astrocytes.