RPS6 and cancer: Furthermore, the data showed simultaneous activation of ribosomal protein S6 (rpS6) and eIF2α signalings and increased expression of ATF4 target genes involved in amino acid supply (1) in the spleen as early as the pre-Cx stage, and (2) in the liver at the onset of cachexia, suggesting upregulation of protein/amino acid metabolism in these organs early during cancer progression.