Figure 6. S6K1 is required for autophagy in mammalian cells. (A) HEK293 cells stably expressing GFP-LC3 were infected with retrovirus encoding a dominant negative S6K1 (K100R) or with lentivirus encoding a specific shRNA directed against human S6K1 and subjected to nutrient withdrawal by replacing supplemented media (Fed) with EBSS for 4 hours (Starved). Representative fields at 63X (oil immersion) magnification are shown. (B) Efficiency of S6K1 knockdown and expression of HA-tagged S6K1 (K100R) in HEK293 GFP-LC3 cells. (C) Quantification of punctae/cell from (A) of at least 9 fields per treatment are represented as a percentage of the starved vector control cells. Error bars represent s.e.m. * (p < 0.0015) ** (p < 0.0002)