Surprisingly, the targeted deletion of Jag1 but not RBPJ in LGR5<sup>+ve</sup> tumor-initiating cells resulted in the silencing of Hes1 expression, disruption of the tumor stem cell niche, and dramatic reduction in the proliferation activity of APC-deficient intestinal tumors in vivo.
Finally, active Notch signaling was verified in the Apc(Min/+) mouse model where Hes-1 mRNA levels were found significantly upregulated in intestinal tumors compared to normal intestinal mucosa.