Fig. 6
KPC1 p.M8V editing attenuates the ubiquitination of p105 and its cleavage to p50. a The effects of wide-type KPC1 (KPC1-WT) and KPC1 p.M8V editing (KPC1-EDT) on the levels of p105 and p50 proteins in QBC939 and RBE cells. b The effects of KPC1-WT or KPC1-EDT on the levels of p105 and p50 proteins in cytoplasmic and nuclear fractions of QBC939 cells. Tubulin and histone H3 were used as the cytoplasmic and nuclear markers, respectively. c The effects of KPC1-WT or KPC1-EDT on processing of p105 to p50 in QBC939 cells by immunofluorescence assays. Scale bars, 20 μm. ***P < 0.001; assessed by Wilcox rank sum test. FIN:C, the ratio of nuclear to cytoplasmic fluorescence intensity. d The effects of KPC1-WT or KPC1-EDT on the protein levels of p105 and p50 in QBC939 cells upon cycloheximide (CHX) treatment (50 μg/mL) for the indicated times. e The effects of KPC1-WT or KPC1-EDT on the p105 and p50 levels in QBC939 cells without or with MG132 treatment (20 μM). f The effects of KPC1-WT or KPC1-EDT on the ubiquitination of exogenous Flag-p105 in QBC939 cells. g The effects of KPC1-WT or KPC1-EDT on the ubiquitination of endogenous p105 in QBC939 cells. h Immunohistochemistry (IHC) assays for the p105/p50 proteins in xenografted tumor tissues from the nude mice of control, KPC1-WT and KPC1-EDT groups. Scale bars, 200 μm. *P < 0.05 and.**P < 0.01; assessed by Wilcox rank sum test. i Co-immunoprecipitation (co-IP) of p105 in QBC939 cells transfected with the indicated constructs using a Flag-specific antibody. Lysates were immunoprecipitated with antibody against Flag followed by immunoblotting with antibodies to Myc (p105-bounded KPC1-WT or KPC1-EDT) and Flag (p105). j Co-IP of KPC1-WT/EDT in QBC939 cells transfected with the indicated constructs using a Myc-specific antibody. Lysates were immunoprecipitated with antibody against Myc followed by immunoblotting with antibodies to Flag (KPC1-WT- or KPC1-EDT-bounded p105) and Myc (KPC1-WT/EDT)