Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Example Input: Bone, as well as the lung and liver, is among the sites of predilection for cancer metastasis. The bone stores large amounts of growth factors such as insulin-like growth factors and transforming growth factor-b, and provides fertile soil for metastatic cancer cells by continuously releasing these bone-stored growth factors, which are a consequence of osteoclastic bone resorption. Metastatic cancer cells in turn produce osteoclast-stimulating cytokines such as parathyroid hormone-related protein( PTH-rP), prostaglandin E2.(PGE2), and various interleukins(ILs). These cancer-produced osteoclast-stimulating cytokines bind to their cognitive receptors and promote the expression of ligands for the receptor activators of nuclear factor kB (RANKL)in osteoblasts. RANKL then binds to its receptor RANK, expressed in pre-osteoclasts, stimulates mature osteoclast formation, and subsequently, osteoclastic bone resorption. This vicious cycle between metastatic cancer cells and osteoclasts is critical to the development and progression of bone metastases. In addition, it is likely that metastatic cancer cells are influenced by bone environments(or niche)and acquire additional capacities such as an epithelial-mesenchymal transition(EMT), allowing them to be resistant to chemotherapy or apoptosis, to survive in a dormant state, or to aggressively spread to distant organs including lung and liver. Thus, the bone can serve as transit port. Disrupting this cycle by inhibiting osteoclastic bone resorption, antagonizing bone-derived growth factors, and neutralizing RANKL or PTH-rP, should be a promising therapeutic intervention for bone metastases. Bisphosphonates(BP)are specific inhibitors of osteoclasts, and have been shown to significantly reduce skeletal-related events(SRE)associated with bone metastasis. Denosumab is a neutralizing monoclonal antibody to RANKL and has recently been found to inhibit SRE more effectively than BP. Further understanding of the crosstalk communication between metastatic cancer cells and bone at the molecular level should lead us to design novel, more effective and specific treatments for cancer patients with bone metastases.
Example Output: To the ligand of which receptors does Denosumab (Prolia) bind?

Example Input: Khin Sok, (Khmer: , born in 1942, Kandal Province, late French colonial Cambodia, died on 10. October 2011 in Paris) was a Cambodian historian, linguist, literature and arts scholar.
Example Output: What is the city of birth of Khin Sok?

Example Input: Facioscapulohumeral dystrophy (FSHD) is a progressive muscular dystrophy caused by decreased epigenetic repression of the D4Z4 macrosatellite repeats and ectopic expression of DUX4, a retrogene encoding a germline transcription factor encoded in each repeat. Unaffected individuals generally have more than 10 repeats arrayed in the subtelomeric region of chromosome 4, whereas the most common form of FSHD (FSHD1) is caused by a contraction of the array to fewer than 10 repeats, associated with decreased epigenetic repression and variegated expression of DUX4 in skeletal muscle. We have generated transgenic mice carrying D4Z4 arrays from an FSHD1 allele and from a control allele. These mice recapitulate important epigenetic and DUX4 expression attributes seen in patients and controls, respectively, including high DUX4 expression levels in the germline, (incomplete) epigenetic repression in somatic tissue, and FSHD-specific variegated DUX4 expression in sporadic muscle nuclei associated with D4Z4 chromatin relaxation. In addition we show that DUX4 is able to activate similar functional gene groups in mouse muscle cells as it does in human muscle cells. These transgenic mice therefore represent a valuable animal model for FSHD and will be a useful resource to study the molecular mechanisms underlying FSHD and to test new therapeutic intervention strategies.
Example Output:
Which disease is associated with the ectopic expression of the protein encoded by the gene DUX4?