To explore the different isoforms of the type IA PI3-kinase (p110α, p110β and p110δ), we performed western blot on lysates from 22 primary neuroblastoma tumors and normal adrenal gland as well as six neuroblastoma cell lines and seven cancer cell lines of different origin (medulloblastoma, cervix, ovary, breast and colon). The gene discussed is PIK3CD; the disease is medulloblastoma.