IL4 and medulloblastoma: IC50 was measured to be 1 ng/mL for three of five medulloblastoma cell lines expressing >900 IL-4 binding sites/cell, 30 ng/mL for D341 cell line expressing ~600 sites/cell, and no marked cytotoxicity at concentrations up to 1000 ng/mL for D283 cell line expressing the lowest level of IL-4R [96].