Expression of p-PYK2 in PBMCs from SLE patients. Detection of p-PYK2 protein in PBMCs from healthy donors (n = 24), patients with RA (n = 32), and patients with SLE (n = 48) was performed by immunocytochemistry technique using specific anti-p-PYK2 Abs. p-PYK2 was weakly positive in PBMCs from healthy donors (A) and RA patients (B). An increase in the positive staining for p-PYK2 was observed in PBMCs from SLE patients (C). Original magnification, × 400. Experiments were repeated at least three times with similar results.