CD24 and medulloblastoma: Injections of 4x105 CD24+ primary Ptch1lox/lox;GFAPcre medulloblastoma cells resulted in 6 tumours from 15 transplantations (95.17+/-19.51 days) while equivalent numbers of CD24- cells gave 0 tumours following 9 injections (p = 0.021, Fig 2C).