ELK1 and cancer: While there were no significant correlations between the levels of ELK1 or phospho-ELK1 and tumor grades or stages, phospho-ELK1 positivity precisely predicted the recurrence of non-muscle-invasive tumors in a univariate setting (P = 0.043) as well as a worse outcome of muscle-invasive tumors in both univariate (P = 0.045 for disease progression; P = 0.008 for cancer-specific mortality) and multivariate (HR = 2.693; P = 0.021 for cancer-specific mortality) settings.