Tyrosine phosphorylation in human dermal fibroblasts exposed to Staphylococcus aureus culture supernatant. Using a cell-based enzyme-linked immunosorbent assay system (RayBiotech, Inc., Norcross, GA, USA), tyrosine phosphorylation was assessed in human dermal fibroblasts exposed to 25 μg of total protein/ml from filtered culture supernatant of S. aureus, 25 μg/ml total protein from S. aureus cell pellet lysate, and in fibroblasts treated with 10 ng/ml each of rhIL-1β and rhTNF-α. These assays were carried out in 96-well plates supplied by the manufacturer. The cells were exposed to various agents for 30 minutes before assaying for tyrosine phosphorylation. The assays were carried out in triplicate. There was significant increase in tyrosine phosphorylation in S. aureus culture supernatant-treated cells similar to IL-1β/TNF-α-treated cells compared with untreated fibroblasts (p < 0.05). IL, interleukin; OD, optical density; SUP, culture supernatant; TNF, tumor necrosis factor.