Fig. 1

Akt/mTOR pathway member protein expression and activation in TfRCC and ccRCC cell lines. a Akt/mTOR pathway member protein expression was determined by Western blot for TfRCC cell lines relative to ccRCC cell lines after 48 h of culture in standard serum-supplemented media. Akt/mTOR pathway activation levels in TfRCC cell lines are comparable to levels in ccRCC cell lines, as shown by similar protein phosphorylation levels of mTOR, Akt, GSK3β, S6 Ribosomal Protein, and 4EBP1. HIF1α expression, a hallmark of ccRCC due to VHL functional loss, is less pronounced in TfRCC than ccRCC cell lines. b Akt/mTOR pathway member protein expression was determined by Western blot after serum starvation versus serum stimulation of TfRCC cell lines. Cells were cultured for 18 h in media without serum supplementation followed by culture for 6 h in the presence (+) or absence (−) of 10% serum supplementation. In the absence of serum stimulation, some levels of phosphorylation are preserved in mTOR, Akt, its kinase target protein GSK3β, S6, and 4EBP1, indicating some constitutive activation of mTORC1, mTORC2 and Akt