KIT and gastrointestinal stromal tumor: As described previously,15 imatinib treatment inactivated KIT and downstream signalling intermediates AKT, MAPK and S6 in imatinib-sensitive GIST-T1 and GIST882, whereas imatinib treatment partially decreased levels of p-KIT, p-AKT, p-MAPK and p-S6 in GIST48, and p-AKT and p-S6 expression in GIST430/654.