MTOR and gastrointestinal stromal tumor: Given that the phosphorylation level of CDC37 at Ser 13 reflects CK2 activity,45 CDC37 and KIT/PI3K/AKT/mTOR signalling inhibition was evaluated by phospho-immunoblot analysis of total cell lysates in imatinib-sensitive cell lines (GIST-T1 and GIST882) and imatinib-resistant cell lines (GIST430/654 and GIST48) after 6 h of treatment with CX4945 (a specific inhibitor of CK2) in serum-free conditions (Fig. 2).