Endothelial cells play an important regulatory role in embryonic development, reproductive functions, tumor growth and progression. In the present study, the suppression subtractive hybridization (SSH) method was employed to identify differentially expressed genes between non-stimulated endothelial cells and activated endothelial cells. Following mRNA isolation of non-stimulated and hepatocellular carcinoma homogenate-stimulated cells, cDNAs of both populations were prepared and subtracted by suppressive PCR. Sequencing of the enriched cDNAs identified a couple of genes differentially expressed, including derlin-1. Derlin-1 was significantly up-regulated by tumor homogenates, VEGF, and endothelial growth supplements in a dose-dependent manner. Knock-down of Berlin-1 triggered endothelial cell apoptosis, inhibited endothelial cell proliferation, and blocked the formation of a network of tubular-like structures. Our data reveal that Berlin-1 is a novel growth factor-responsive endothelial antigen that promotes endothelial cell survival and growth. (c) 2006 Elsevier Inc. All rights reserved.