GLI1 and colorectal cancer: Comparable to the elevated Gli activity, PGE2 increased the proliferation of all of these tested colorectal cancers cells in a Gli-dependent manner, as revealed by the inhibitory effect of either Gli inhibitors GANT61 and JQ1 (Fig. 1E), or genetic silencing Gli2 by small interfering RNA (siRNA) (Fig. 1F, G).