Cytokeratin 8 (CK8) and smooth muscle actin (SMA) IHC analyses showed that prostate tumors in Pb-T2-ERG;Trp53pcR172H/- mice at 15 months were CK8-positive, but SMA staining was not observed (Supplementary Fig. 2d), suggesting that these tumors are luminal type with an invasive phenotype. Here, ERG is linked to prostate neoplasm.