PDGFRA and malignant colon neoplasm: SHH has been reported to control the proliferation of several cell types through various molecular mechanisms such as increase in PDGFRα and Bcl-2 expressions, decrease in DRs and Fas expressions, and inhibition of PARP cleavage and caspase-3 activation in colon cancer cell lines overexpressing Gli genes [41] or, an overexpression of dominant-negative FADD in cells expressing SHH or a constitutively active Smoothened [41].