A, Endothelial cells treated with or without ATP (100 µmol/L, 5 minutes) were used for caveolae isolation. The caveolae are a repository of proteins related to ATP and NO regulation; classification of 75 most enriched proteins in the caveolae showed that 56.3% (shaded with circles) of the total number of proteins were related to NO or ATP. B, Analysis of normalized enrichment score, an estimate of the enrichment of proteins in each category, did not reveal a main effect of ATP treatment. Independent of ATP treatment, NO-related (*), ATP-related (†), and cell function-related ($) protein categories were significantly greater than all of the other categories, including those related to transport, histone, enzymes, structure, and adhesion. & denotes categories that were significantly different from adhesion group alone.