Agilent gene expression array Log2 signal intensities of LNCaP (ERG-) and VCaP (ERG+) cells, primary PCa, and CRPC metastases. Based on ERG microarray expression Cy3 values primary PCa specimens were divided into those with low (<2750), medium (>2750 <20,000) and high (>20,000) levels of ERG expression. Of note, the CRPC metastases group contains a large cohort of medium ERG expressors.