Hypoxic Activation of K-Ras Figure 4. K-ras and Src enhance the survival of colon cancer cells in hypoxia. A, DLD1, HCT116 and Caco2 cells were transfected with control siRNA or K-ras siRNA, and then incubated in hypoxia for 48 hours. Cell numbers were determined using a hemacytometer after staining with trypan blue and the results are expressed as percentages of viable cells compared with siRNA control transfected cells in normoxia. The data are from three independent experiments and shown as mean 6 SD. *, P,0.05; **, P,0.01. B, Colo320DM cells grown on sterile coverslips were transfected PLoS ONE | www.plosone.org 6 June 2010 | Volume 5 | Issue 6 | e10966