Id4 expression in prostate cancer as determined from publically deposited microarray databases. The Oncomine database was queried against Id4 and all prostate databases were analyzed. The box and whisker plots from four of these representative studies is shown [51–54]. Consolidated data from all these studies demonstrated that Id4 is significantly (T-values > 5 and low P-values < E-6) down-regulated in prostate cancer samples. Abbreviations: n: No. of samples in each analysis, PC: Prostate Cancer (Red), MPC: Metastatic prostate cancer (Yellow), NAP: Normal adjacent prostate (Blue), NP: Normal Prostate (Blue), PP: Post-pubertal prostate (Blue), BP: Benign prostatic hyperplasia (Blue), PIN: prostate intra-epithelial neoplasia (green).