Taken together, consistent results were obtained in glioblastoma cell lines U-87 MG, U-373 MG and T98G with different genetic background, suggesting that p110α is most essential among three class IA PI3K catalytic isoforms, which may be due to its predominant role in RTK-mediated PI3K signaling. The gene discussed is PIK3CB; the disease is glioblastoma.