(c) In HeLa cells, AMBRA1 was downregulated by RNAi. Protein extracts were immunoprecipitated using anti-ULK1 antibody or with IgG as a negative control. Purified complexes and total extracts were analysed by western blotting using anti-ULK1, anti-Lys-63 ubiquitin and anti-AMBRA1 antibodies. Of note, ULK1 levels in the co-immunoprecipitation experiment do not change in this case in the AMBRA1 siRNA lane, owing to saturation of the anti-ULK1 antibody (see also Fig. 4h). 