CD4 and holoprosencephaly: It was assumed that HPE-type HSP might occur in hNOJ mice, as described elsewhere [27], [28]; therefore, we examined the IFN-γ-producing capacity of CD4+ T cells isolated from the spleens of hNOJ (IR+) and hNOJ (IR−) mice (n = 3 and n = 3, respectively) during the later phase (16 and 26 wk, respectively) post-transplantation by stimulating them with or without PMA plus ionomycin.