LLnL does not inhibit tyrosine phosphatase activity. Growing Ba/F₃ cells were washed and lysed with NP-40 buffer in the absence of vanadate. Lysate from 10⁵ cells was assayed for total tyrosine phosphatase activity. LLnL (▨) (50 μmol/L) or DMSO (□) as carrier were added to the reaction at a final concentration identical to that used when added to cell cultures. As a positive control, orthovanadate (▧) (1 mmol/L) was also added to inhibit phosphatase activity. Data were normalized to activity obtained from control reactions (no additions [▪]) and each bar represents the average of duplicate samples taken from a single experiment. Identical results were obtained from several experiments using different dilutions of lysate.