S100A4 protein serves as a direct signaling target of receptor tyrosine kinase 2 (ERBB2) in medulloblastoma through a pathway involving phosphatidylinositol 3 kinase AKT (PI3K/AKT), which is ultimately blocked by the ERBB tyrosine kinase inhibitor OSI774 [53]. The gene discussed is ERBB2; the disease is medulloblastoma.