Fig. 6: Pathophysiological relevance of the TGFβ/Nur77/ID1 axis in colon cancer.

a Cells pretreated with MG132 (20 μM) for 2 h were then treated with TGFβ (10 ng/mL) for 1 h. ID1 ubiquitylation and mRNA expression were examined by co-immunoprecipitation and qRT-PCR, respectively. Ub ubiquitin. Two-tailed unpaired Student’s t test was used for statistical analysis, and data are presented as means ± SD (n = 3 biologically independent samples). b Cells were treated with TGFβ (10 ng/mL) for 1 h and protein expression was examined by immunoblotting using the indicated antibodies. c SW620 cells were treated with MG132 for 2 h and then with TGFβ at the indicated doses for 1 h. ID1 ubiquitylation and protein interactions were examined. d, e SW620 (d) and HCT116 (e) cells were treated with TGFβ at the indicated doses for 1 h. IB and qRT-PCR were applied to examine protein and ID1 mRNA expressions, respectively. The phosphorylation of Smad2 and Smad3 were detected using anti-p-Smad2(S465/467) and anti-p-Smad3(S423/425) antibodies, respectively. Two-tailed unpaired Student’s t test was used for statistical analysis, and data are presented as means ± SD (n = 3 biologically independent samples). f, g Immunohistochemistry analysis of clinical colon cancer samples showing correlations of ID1 expression with Nur77 expression and TGFβ signal activity. The green (n = 22) and red (n = 33) dots represented tissue samples with low and high TGFβ signal activity, respectively (f). The green (n = 5) and red (n = 11) dots represented tissue samples with low and high Nur77 expression, respectively (g). Two-tailed correlation analysis was used to indicate correlation (assume data were sampled from Gaussian population). Data represent at least two independent experiments. Source data are provided as Source Data file.