MCL1 and gastrointestinal stromal tumor: In line with these studies, our finding that OPN exhibited significant anti-apoptotic effects in GIST, and specifically in the presence of imatinib, through anti-apoptotic protein Mcl-1 up-regulation, may be of value in supporting the rationale for development of new pharmaceutical strategies against imatinib-resistant GIST, which may be common in patients with disease recurrence or progression after imatinib treatment[6,7].