Monocytes contain little caveolin-1 compared to fibroblasts and endothelial cells. Human umbilical vein endothelial cells (Endo), NLF (Fib), and Normal monocytes (Mono) were extracted using SDS-PAGE sample buffer. (A) 10 μg each Endo and Fib extract and 30 μg Mono extract were Western blotted for caveolin-1 and actin (loading control). Similar results were obtained when GAPDH was used as the loading control (not shown). (B) Three times as much of each sample was loaded to allow the detection of caveolin-1 in Mono.