GLI1 and prostate carcinoma: Altogether, these data demonstrate that Shh-expressing prostate cancer cells can directly and specifically induce differentiation in pre-osteoblasts via a Gli1-dependent mechanism that does not require transcriptional upregulation of Runx2. Paracrine activation of the Shh pathway in osteoblast progenitors and subsequent induction of osteoblast differentiation could be a mechanism through which high levels of Shh expression in prostate carcinoma contribute to bone metastasis.