DDR2 and hepatocellular carcinoma: DDRs, unique tyrosine kinase receptors that function as a sensor ECM, are implicated in a wide range of cellular processes.20 Our results show that DDR1 rather than DDR2 is overexpressed in UM cells as well as specimens from patients with UM, which is in line with the previous studies that DDR1 expression is restricted to epithelial cells in solid tissues.21 DDR1 is reported to be also overexpressed in melanoma arising from cutaneous melanocytes.22 In addition, DDR1 is overexpressed in prostate cancer, glioma, and human hepatocellular carcinoma.20