p85β degradation regulates cell autophagy. (a) During a 72-h serum starvation, NHFs were transfected with either siRNAs targeting FBXL2 (no. 1 or 2) or a non-silencing siRNA (NS). Cells were subsequently stimulated with media containing serum and collected at the indicated time points for immunoblotting. SR, serum re-addition. (b) During a 72-h serum starvation, NHFs were transfected with either siRNAs targeting FBXL2, both FBXL2 and p85β, or a non-silencing siRNA (NS). Cells were subsequently stimulated with media containing serum and collected at the indicated time points for immunoblotting. SR, serum re-addition. (c) U2OS cells stably transfected with a doxycycline-inducible p85β construct were serum starved for 48 h. During the last 16 h before collection, p85β expression was stimulated with doxycycline. Cells were subsequently stimulated with media containing serum and collected at the indicated time points for immunoblotting. SR, serum re-addition. (d) Cells constitutively expressing GFP–LC3 were transfected with HA-tagged p85β, fixed and incubated with an anti-HA p85β antibody (red). Arrows in the top panels point to the enhanced autophagic response (LC3-II vesicles) in cells expressing high levels of p85β, as shown in the bottom panels. Uncropped images of blots are shown in Supplementary Fig. S8. Scale bars, 10 μm.