KIT and gastrointestinal stromal tumor: On the other hand, the prognostic data of miRNA221/222 cluster members is in some way inconsistent with previous pre-clinical results, where the overexpression of miRNA221 and miRNA222, in GIST cell lines, inhibited cell proliferation, disturbed cell cycle progression and increased apoptosis [41, 50] by a signaling cascade that may involve KIT, AKT and BCL2 [50].