MTOR and renal cell carcinoma: When KPT-330 resistant cells were treated with each of the currently approved for RCC kinase inhibitors (sunitinib and sorafenib) and mTOR inhibitors (everolimus and temsirolimus), R1 and R2 cells retained sensitivity similarly to P cells (Fig. 7), implying that the conventional targeted therapeutics could be utilized as second line therapy if patients develop resistance to KPT-330.