L-744,832 inhibits H-Ras farnesylation in murine hematopoietic cells. Mononuclear cells harvested from the bone marrows of mice transplanted with wild-type or Nf1−/− cells were cultured for 20 hours. Cells were either untreated (U) or were cultured with either 10 μmol/L or 25 μmol/L of L-744,832 or with 100 μmol/L of compactin. The cell lysates were prepared and H-Ras processing was assessed as described in Fig 1. Unprocessed H-Ras is indicated by the white arrow and processed Ras is designated with a black arrow.