Fig. 1. Growth and morphology of wild-type and HIF-1-null epiphyseal chondrocytes. (A) The growth curves of wild-type chondrocytes compared with cells with Cre-recombinase-induced deletion of HIF-1. The increase of HIF-1-null chondrocytes (exponential phase) is strongly retarded compared with wild-type cells. All data points are representing means ± standard deviations of duplicates from two independent experiments. All cells were infected with MOI 100 of adenovirus containing either Cre recombinase or ß-galactosidase. In the lower panel, wild-type chondrocytes (+/+) on days 3 (B) and 5 (D) post-plating are compared with mutant chondrocytes lacking HIF-1 (-/-) (C,E). For the first few days in mutant cultures, single chondrocytes showed a bipolar or stretched cell shape. At day 5 post-plating, chondrocytes from both cultures were mostly confluent and appeared round or polygonal (D,E).