EIF4EBP1 and neoplasm: ,7 Although both regions showed a similar fluorescence signal intensity for total 4EBP1 protein, NK displayed a minimal signal for pSer65-4EBP1 (<1% of cells), but sections of ccRCC showed a significantly higher signal in tumor cells (approximately threefold increase in grade 2 tumors), which further increased as tumor grade progressed (approximately eightfold in grade 4 tumors).