(g) HEK293 cells were transfected with scramble siRNA or ATG13 siRNA. Protein extracts were immunoprecipitated using ULK1 antibody or IgG. The band density ratio of immunoprecipitated AMBRA1 relative to immunoprecipitated ULK1 is analysed, with the control ratio arbitrarily defined as 1.00. n = 3 extracts prepared from independent experiments; data are presented as means±s.d. and significance is P = 0.04. Uncropped images of blots/gels are shown in Supplementary Fig. S6. Source data of statistical analysis are shown in Supplementary Table S1. 