Fig. 4.

Plakoglobin maintains β-catenin–dependent transcription. (A) Transcript levels of selected β-catenin downstream target genes c-Myc, Axin2, and Tcf7 were assessed by RT-PCR. Data were normalized to Gapdh. Ctnnb1^+/+ErbB2^KI, n = 8; Ctnnb1^fl/+ErbB2^KI poor differentiation, n = 6; Ctnnb1^fl/+ErbB2^KI others, n = 6; Ctnnb1^fl/flErbB2^KI, n = 5. Error bar: SEM. ns, Not significant. *P < 0.05 (Student’s t test). (B) Immunoblot analysis illustrates comparable protein levels of β-catenin target genes Axin2 and Cyclin D1. (C) The heat map shows unsupervised clustering analysis of gene expression profile from end-point tumors. Expression of plakoglobin is indicated as + (high or up-regulated) or − (low or unexpressed) to show that expression of plakoglobin alone is sufficient to segregate heterogeneous Ctnnb1^fl/+ErbB2^KI tumors into two distinct groups: (i) high plakoglobin tumors that are well-differentiated and cluster with Ctnnb1^+/+ErbB2^KI tumors and (ii) low plakoglobin tumors that are poorly differentiated and form their own unique group.