Myosin light chain kinase inhibitors can block the internalisation of surface expressed viral antigens. A range of serine/threonine kinases were tested for their importance during the internalisation process using chemical inhibitors: Bisindolylmaleimide (PKC inhibitor), H-89 (PKA inhibitor), PKG inhibitor, KN-93 (CaM-dependent kinase II inhibitor), ML-7 (MLCK inhibitor). (A) Confocal images of feline monocytes after an internalisation assays of 30 min using antibodies or control ligands: beads or transferrin. In row 2, cortical actin was stained (red) to visualise whether or not the lamellipodia were closed around the beads. The images show a single optical section through the cell, scale bar indicates 5 μm. (B) Quantification of the internalisation in presence of inhibitors against serine/threonine kinases. Results are given relatively to a control of untreated cells. Data are means and standard deviations of triplicate assays. The asterisk marks results that are significantly different from the untreated control (p < 0.05).