Fig. 2. LTBP-1 protein is overexpressed in AhR–/– MEF. (A) LTBP-1 protein expression was analyzed using cellular extracts from wild-type and AhR-null MEF. A total of 15 µg protein were resolved in SDS-PAGE gels and used for immunoblotting with a specific anti-LTBP-1 `hinge' antibody. The position of the 190 kDa LTBP-1 band is indicated. (B) LTBP-1 was immunoprecipitated from conditioned medium from MEF of both genotypes and subjected to immunoblot analysis as indicated above. The position of the 190 kDa LTBP-1 band is indicated. (C) LTBP-1 overexpression was also detected in the extracellular matrix of AhR–/– MEF by immunocytochemistry using the `hinge' antibody. A significant increase in matrix deposition could be observed in MEF lacking AhR (arrowheads). Quantitations of protein expression were done as indicated in Fig. 1, except for B, in which ß-actin normalization could not be applied. The experiment was performed in three different MEF cultures for each genotype with similar results.