The effect of IFN-γ on the amount of cPLA₂ protein. HL-60 cells were incubated with 2,000 U/mL of IFN-γ for indicated times and homogenized as described in Materials and Methods. Particulate and soluble fractions from HL-60 cells were subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), transferred to nitrocellulose, and immunoblotted with rabbit antihuman cPLA₂ antibody. A representative Western blot of membrane pellet (upper) and crude cytosol (lower) from HL-60 cells is shown. The cPLA₂ protein was shown from left as follows: control cells (lane 1), cells treated with IFN-γ (2,000 U/mL) for 30 minutes (lane 2), 4 hours (lane 3), 12 hours (lane 4), 48 hours (lane 5), and 120 hours (lane 6). The size of the molecular marker is indicated on the left side.