To examine the possible effects of EphB1 on radiosensitivity in vivo, we generated a genetically engineered EphB1 knockout mouse medulloblastoma model (EphB1−/−Smo) by crossing the transgenic ND2-SmoA1 medulloblastoma line [17] with our mice deleted of EphB1 [19, 20]. The gene discussed is EPHB1; the disease is medulloblastoma.