Fig. 1. Expression of PTN and SDF-1 is JUN dependent. (A) Expression profiling of wild-type versus Jun^–/– mouse embryonic fibroblasts revealed Ptn and Sdf-1 to be activated by JUN. Enhanced transcript levels in wild-type cells (black bars) are indicated as fold difference compared to the expression in Jun^–/– cells (white bars), which was set as 1. Kgf, representing a known direct JUN target, the JUN-repressed disabled homolog 2 (Dab2) and the JUN-independent genes lipocalin (Lcn2) and CD24a antigen (cd24a) were included as controls. (B) Validation of the microarray results by semi-quantitative RT-PCR on cDNA derived from untreated and IL-1-stimulated fibroblast monocultures. Expression of the JUN-activated cytokines Ptn, Sdf-1 and Kgf was impaired in fibroblasts lacking JUN activity, whereas Cxcr4, Lcn2, Dab2 and Cd24a levels were not reduced. ß-tubulin 1 (Tubb1) was used for standardization.