KIT and gastrointestinal stromal tumor: KIT, another RTK, undergoes gain-of-function mutation in >90% of gastrointestinal stromal tumours (GISTs) leading to the activation of PI3K-AKT, mitogen-activated protein kinase (MAPK), STAT-1 and STAT-3 prosurvival pathways (Duensing et al, 2004).