GLI1 and cancer: Compellingly, in the presence of cancer cell derived conditioned medium, IMR90 fibroblasts showed an increased level of Shh mRNA expression (Figure 8A) and Gli mRNA transcription, target of Shh signaling activation (Figure 8B), suggesting that paracrine factors produced by cancer cells can increase Shh production levels in stroma, which then potentiates tumor expansion, local migration, and invasion.