KDR and nonpapillary renal cell carcinoma: To determine the relevance of this pathway for TNFR2‐mediated pSTAT3Ser727 signaling, cells were pretreated with specific inhibitors to these kinases––SU5408, BMK120, AZ5363 or Ku0063794 (VEGFR2, PI‐3K, Akt, and mTOR, respectively) and each decreased R2TNF‐induced pSTAT3Ser727 formation by ~4‐fold in ccRCC‐CD133+CSCs (Figure 4A, quantified in B).