Induction of cells proliferation by PYK2 activation in PBMCs from patients with active SLE, but not those from normal individuals and RA patients. Isolated human PBMCs were cultured for 24 h in 96-well flat-bottomed microtitre plates with medium, PMA (1 ng/ml) or pretreated with the PYK2 inhibitor TyrA9 (5 μM) for 1 h before the addition of PMA, and then the cultures were pulsed with [3H]-thymidine (1.0 μCi/well) 18 h before harvesting the cells, and [3H]-thymidine incorporation was measured. The mean ± SD of the counts per minute value from triplicate samples is shown. The experiments were performed more than three times, and a representative data set is presented. * = P < 0.05.