reverse transcription PCR was used to find out which key aspects of the Notch pathway were expressed in cancer of the colon cells. MCF 7 cells were shown to have activated Notch signaling. Human umbilical vein endothelial cells were used as a control cell line for Notch1 4 expression. Three Notch receptors with the exception of Notch and Notch4 target genes were expressed in SW480 and DLD 1 cells, and Hes5 was expressed in cells. Next, we analyzed Hes1, Hey1, and Hey2 expressions in 21 surgically resected colorectal cancer specimens by real-time RT PCR to determine whether the Notch pathway was mixed up in clinical specimens. Everolimus RAD001 Hes1, Hey1, and Hey2 messenger RNA words were greater in cyst cells than in matched usual mucosae in 18, 7, and 1-1 of 21 colon cancer specimens, respectively. Only 4 of 21 a cancerous colon specimens simultaneously showed improved Hes1, Hey1, and Hey2 expressions in cancer cells in contrast to matched normal mucosae. These results suggest that activation of the Notch pathway could be possible but is not certain in clinical specimens. We next quantitatively examined Notch signaling inhibition by DAPT in colon cancer cells. Immunoblots of SW480 cells transfected with the mNotch Elizabeth construct revealed smaller bands addressing NICD, which became undetectable after treatment with DAPT. Transfection of mNotch E light emitting diode to an estimated 6 fold increase in CBF1 reporter luciferase activity due to constitutive secretase bosom, Plastid nevertheless the addition of DAPT suppressed luciferase activity to near baseline level. DAPT com-pletely inhibited the synthesis of endogenous cleaved Notch 1 and suppressed the expression of Hes1 mRNA in SW480 and DLD 1 cells. These results show that DAPT can nearly com-pletely block Notch signaling in the levels we found in our experiments in these cells. To examine whether this reduction in the Notch pathway by DAPT contributes to the increase in TXLinduced mitotic arrest and apoptosis, we silenced Notch3, Notch2, and Notch1, respectively, by RNA interference. Transfection of siRNA Flupirtine targeting Notch1, Notch2, and Notch3 triggered an 80% o-r higher knock-down of Notch1 3 and Notch1 3 protein expressions in SW480 cells. But, knock-down of Notch1 3 didn’t lead to enhanced TXL induced mitotic arrest and apoptosis compared with control. Knockdown of CBF1 did not also result in increased TXL induced mitotic arrest and apoptosis in contrast to control. Finally, to look at the therapeutic potential of the combined use of TXL and secretase inhibitors in vivo, we used a colon cancer xenograft model. Subcutaneously injected SW480 cells gave rise to exponentially expanding tumors in athymic nude mice. Treatment with car or DAPT alone did not affect the kinetics of tumefaction growth.