Time- and concentration-dependent responses to PAR^39-44. (A) Mock-transfected BaF3 cells (open circles) or BaF3/PAR-2 cells (closed circles) were plated as outlined in the legend to Fig 1 and incubated with progressive concentrations of PAR^39-44 or SLIGRL (closed squares) for 48 hours before MTT analysis. (B) BaF3/PAR-2 cells were studied in the identical fashion for variable periods of time as delineated. All experiments were completed in WEHI⁻ media. Results are expressed as the mean ± SEM of four wells from a single set of experiments.