Given a question and a context passage, generate the answer having the word or phrase from the context passage. Here, the answer should be a shortest continous span from the passage.

Ex Input:
Context: Konstantinos Raktivan (Greek: ; 1865 -- 21 May 1935) was a Greek jurist and politician, who served as cabinet minister, as the de facto first Governor-General of Macedonia, president of the Athens Bar Association and of the Council of State, Speaker of the Hellenic Parliament and member and president of the Academy of Athens. 
 Question: Who led Konstantinos Raktivan?

Ex Output:
academy of athens


Ex Input:
Context: Chronic lymphocytic leukemia (CLL) cells depend on microenvironmental factors for proliferation and survival. In particular, the B-cell receptor (BCR) and nuclear factor- B (NF-B) pathways are activated in the lymph node (LN) microenvironment. Thus, model systems mimicking tumor-host interactions are important tools to study CLL biology and pathogenesis. We investigated whether the recently established NOD/scid/c(null) (NSG) mouse xenograft model can recapitulate the effects of the human microenvironment. We assessed, therefore, tumor characteristics previously defined in LN-resident CLL cells, including proliferation, and activation of the BCR and NF-B pathways. We found that the murine spleen (SP) microenvironment supported CLL cell proliferation and activation to a similar degree than the human LN, including induction of BCR and NF-B signaling in the xenografted cells. Next, we used this model to study ibrutinib, a Bruton's tyrosine kinase inhibitor in clinical development. Ibrutinib inhibited BCR and NF-B signaling induced by the microenvironment, decreased proliferation, induced apoptosis and reduced the tumor burden in vivo. Thus, our data demonstrate that the SP of xenografted NSG mice can, in part, recapitulate the role of the human LN for CLL cells. In addition, we show that ibrutinib effectively disrupts tumor-host interactions essential for CLL cell proliferation and survival in vivo. 
 Question: What is the name of Bruton's tyrosine kinase inhibitor that can be used for treatment of chronic lymphocytic leukemia?

Ex Output:
ibrutinib


Ex Input:
Context: Osteoporosis and several other bone disorders occur when there is an imbalance between the resorption and formation components of bone remodeling activity. Therapies available for some of these conditions modulate the activity of osteoclasts and/or osteoblasts. The recent discoveries of receptor activator of NF-kappaB ligand (RANKL), an endogenous activator of osteoclastogenenesis and osteoclast activity and its inhibitor, osteoprotegerin (OPG) as pivotal regulatory factors in the pathogenesis of bone diseases like osteoporosis provide unique targets for therapeutic agents. In laboratory animals and now in humans, administering forms of OPG markedly inhibits osteoclast activity and improves bone strength, documenting that the strategy of inhibiting RANKL activity has therapeutic promise. A highly specific, fully human antibody against RANKL has been produced (denosumab) that in early studies in humans reduces bone turnover and improves bone density. Attributes of denosumab in these clinical studies include a very rapid onset of action, sustained effects for several months after a single injection, and good tolerability. These results provide the basis for studies evaluating the effectiveness of denosumab in several clinical conditions characterized by increased osteoclastic activity. 
 Question: To the ligand of which receptors does Denosumab (Prolia) bind?

Ex Output:

rankl