However, this concept has recently been challenged as depletion of α-SMA+ myofibroblasts in genetically-engineered murine models of pancreas cancer accelerates tumor progression 3; Genetic reduction or pharmacologic inhibition of sonic hedgehog (Shh) pathway resulted in reduced stromal content with more aggressive tumors in KPC mice 4, 5, and a similar phenomenon was simultaneously reported in type I collagen (Col1) deficient tumors 6. The gene discussed is ACTA1; the disease is neoplasm.