PIK3CA and neuroblastoma: Although both pan-PI3K inhibitors (copanlisib and pictilisib) in our study were more effective than p110α selective inhibitor alpelisib in vitro, the inhibition on neuroblastoma cell growth by alpelisib was not further enhanced by either TGX-221 or idelalisib (Additional file 1: Fig. S6a, b), suggesting that p110α is the prevailing catalytic isoform in neuroblastoma cells among the class IA PI3Ks.