Wild-type and oncogenic Ras differentially regulate cell proliferation. Wild-type and oncogenic Ras differentially regulate cell proliferation. Cells were transfected with various combinations of siRNAs targeting either the oncogenic or wild-type Ras isoforms. Two days after transfection, cells were counted and seeded in triplicate at equal densities in complete medium. Cell counts were obtained every 24 hours using a Coulter particle counter. An initial cell count was obtained at the time of seeding to confirm equal seeding densities. Values represent the fold-change in cell count relative to the 48-hour timepoint. NS, non-silencing control; H1, H2, H3, 3 independent siRNAs targeting HRAS; K1, K3, 2 independent siRNAs targeting KRAS; N1, N2, N3, 3 independent siRNAs targeting NRAS. Amy Young et al. Cancer Discovery 2013;3:112-123 ©2013 by American Association for Cancer Research