L-744,832 inhibits H-Ras farnesylation in cultured cell lines. COS 7 or THP-1 cells were cultured for 48 hours, lysed, immunoprecipitated with pan-Ras antibody Y13-259, blotted, and probed with an antibody specific for H-Ras. Cells were either untreated (U) or were cultured with either 10 μmol/L or 25 μM of L-744,832 or with 100 μmol/L of compactin. Unprocessed H-Ras is indicated by the white arrow and processed Ras is designated with a black arrow.