We investigated the expression of glucose transporter (GLUT) protein isoforms in two human retinoblastoma cell Lines, Y79 and WERI-Rb1, by Western blotting analysis with anti-GLUT1,2,3, and 4 antibodies. GLUT1 and GLUT4 proteins were detected in Y79, whereas GLUT1 and GLUT3 proteins were found in WERI-Rb1. GLUT2 protein was not detected in Y79 or WERI-Rb1. Our findings are of interest because (1) the expression of GLUT protein isoforms in the two retinoblastoma cell lines was different, and (2) GLUT4, protein, the insulin-sensitive GLUT isoform, was detected in Y79. This suggests that these cell lines have different mechanisms of glucose transport. (C) 1997 Japanese Ophthalmological Society.