c-met Expression in activated CD68⁺ monocytes obtained from normal PBMNCs. Combined in situ hybridization/immunocytology was performed with a c-met [³⁵S] RNA-probe together with T-cell and monocyte-specific antibodies. Cell surface staining was performed with a rabbit polyclonal antihuman CD3 antibody (A) and a mouse monoclonal antihuman CD68 antibody (B and C). Note the specific hybridization signal (accumulation of black grains) in the CD3-negative cell population (A) and the CD68-positive cell population (B, large arrows: markedly positive cells; arrowhead: slightly positive cell; small arrows: negative cells). (C) Shows negative control hybridization with a c-met sense probe in combination with immunocytology for CD68.