Fig. 4: CK1δ is required for SPOP-mediated ASCT2 degradation.

a HEK293 cells were transfected with indicated plasmids, followed by immunoprecipitation with FLAG-agarose beads and immunoblotting. b HEK293 cells were transfected with various FLAG-CK1 isoforms, immunoprecipitated with FLAG-agarose beads and analyzed by immunoblotting. c Endogenous CK1δ protein in SUM159 cell lysates were pulled down with anti-S CK1δ antibody, and associated ASCT2 were detected by immunoblotting with anti-ASCT2 Ab (top, IP). Cell lysates were subjected to immunoblotting (bottom, input). d MDA-MB-231 cells were transfected with indicated CK1 isoforms, then analyzed by immunoblotting. e MDA-MB-231 cells were transfected siRNA targeting CK1δ for 48 h, followed by immunoblotting. f HEK293 cells were transfected with FLAG-SPOP and HA-ASCT2 and treated with D4476 for 12 h before harvesting, followed by immunoprecipitation with FLAG-agarose beads and analyzed by immunoblotting. g MDA-MB-231 cells were treated with different concentrations of CK1 inhibitor D4476 for 24 h, then analyzed by immunoblotting. h, i MDA-MB-231 cells were transfected with si-NC or siRNA targeting CK1δ (si-CK1δ#1), then incubated with CHX for various time points, and analyzed by immunoblotting ies (h), the band density of ASCT2 was quantified using ImageJ software and normalized to α-tubulin (mean ± SD, n = 3) (i). j HEK293 cells were transfected with indicated plasmids, lysed under denaturing conditions, followed by Ni-beads pulldown, and immunoblotting for ASCT2. Source data are provided as a Source Data file.