Figure 2: Positive correlation of Smurf1 expression with Nedd8 and its interacting enzymes in colorectal cancer.

(a) Representative images from immunohistochemical staining of Smurf1, Ubc12, NAE1 and Nedd8 in the same colorectal cancer tumour. Scale bars, 100 μm. (b–d) The expression scores of Nedd8 (b, n=283 ), NAE1 (c, n=281) and Ubc12 (d, n=190) were compared between colorectal cancer tumours and matched adjacent normal tissue using the Wilcoxon test. Any outliers are marked with a circle. (e) Representative images from immunohistochemical staining of Smurf1, Nedd8, NAE1 and Ubc12 expression in four serial sections of the same tumour from three cases. Scale bars, 100 μm. (f–h) Box plot of NAE1, Ubc12 and Nedd8 expression in colorectal cancer from 298 subjects. The subjects were divided into three groups based on Smurf1 expression scores in the tumours, representing low (scores 0–7), medium (scores 8–10) and high (scores 11–12) expression of Smurf1. Data were analysed by Kruskal–Wallis test. (i) Colorectal cancer tissues were compared with matched adjacent normal tissues using the Wilcoxon test (n=30). Any outliers are marked with a circle. Representative images of immunohistochemical staining of NEDP1 expression in the same tumour from three cases are shown. Scale bars, 400 μm. (j) Box plot of NEDP1 expression in colorectal cancer from 30 subjects. The subjects were divided into three groups based on Smurf1 expression scores in the tumours. Data were analysed with the Kruskal–Wallis test.