a, MEFs were deprived of glucose in the absence (left) or presence (right) of MG132 (5 µg ml−1) and subject to immunoblotting. b, In vivo ubiquitination assay of wild-type CARM1 or ubiquitination-defective K471R mutant CARM1. HA, haemagglutinin; HM, HisMax tag. c, Identification of CARM1-interacting proteins. F–CARM1 denotes Flag-tagged CARM1 construct. d, Interactions between SKP2 and protein arginine methyltransferases (PRMTs) were analysed. e, Glucose-starved cells were subjected to immunoblotting. f, g, In vivo ubiquitination assay of CARM1. h, Representative confocal images. Scale bar, 20 µm. i, Schematic of SKP2-containing SCF E3 ligase-dependent degradation of CARM1.