In HT29 multi-cellular tumor spheroids, the combination treatment of gemcitabine plus V158411 reduced Chk1 auto-phosphorylation (S296) and increased Chk1 phosphorylation at S345 and γH2AX levels albeit at higher concentrations of V158411 than that required under normal anchorage dependent growth conditions (Figure 8B). This evidence concerns the gene CHEK1 and neoplasm.