Fig. 5

Cytosolic CDH4 suppresses the ubiquitination/degradation of β-catenin. A The expression of CDH4, β-catenin, and active β-catenin in the cytomembrane (CM), cytoplasm (CP), and cell nucleus (CN) was detected by WB. B Overexpression of CDH4 in PTC cells enhanced the expression of β-catenin and active β-catenin in the whole cell lysates, cytoplasm, and cell nucleus. C Knockdown of CDH4 inhibited the expression of β-catenin and active β-catenin. D Immunofluorescence analysis showing the decreased intensity of active β-catenin in TPC-1 cells transfected with CDH4 shRNA. E, F Half-life analysis of β-catenin abundance in CDH4 knockdown or control TPC-1 (E) and BCPAP (F) cells for the indicated periods in the presence of CHX (100 µM). The β-catenin level was normalized to GAPDH, and quantification of β-catenin stability is shown on the right. ***P < 0.001, two-way ANOVA test. G TPC-1 and BCPAP cells were transfected with CDH4 shRNA or a control vector for 48 h, followed by treatment with MG132 (20 μM) for an additional 6 h before WB analysis. H Immunoblotting analysis of the ubiquitination of endogenous β-catenin in PTC cells transfected with CDH4 shRNA, CDH4-overexpressing vector, or corresponding control vector