CD28 and hereditary spastic paraplegia: Consistent with the previous findings (Tani-ichi et al., 2005) and as demonstrated in the present analysis of the peripheral blood T cells from our HSP patient and controls (Figure 3), activation by anti-CD3/CD28 markedly enhanced B4GALNT1 gene expression and GM2S activity, resulting in the up-regulated expression of GM1 in T cells.