instruction:
Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
question:
Modeled after US hot website.com, group buying websites are now popular in China. These websites use the power of group buying to get competitive discounts for a daily deal on some best stuff to do, see, eat and buy in the cities across China. Discounts are available within just one click. Zhao lei, a software engineer in Beijing, loves the one-hour lunch break at noon,as it is the best time for him to check "today's special" at his favorite group buying websites . Sometimes he searches for great deals at directory sites devoted to the new shopping space. Zhao spends around 800 yuan($117.65) on group buying every month, mostly to buy food coupons for eating at some nice restaurants and occasionally to find something fun to do. " I love group buying. In addition to the competitive discounts it offers, it helps me get something fun, exciting and new, and such surprises give me a reason to try something new," he said. When he finds a really good bargain, he will send the link to friends or colleagues through MSN,QQ, or e-mail, or share the information at some social networking websites. In doing so, he often gets a certain cut off the price. At some sites, buyers are invited to leave notes about what they want to buy and the website will consider it if similar applications reach a certain number. That is how Zuo got her digital camera after waiting for two months. "It is cool. I want to buy a new digitgal camera for my trip to Switzerland this winter, but I never expected such cheap prices!" Zuo said.
answer:
What is the passage mainly about?


question:
The TNF family member receptor activator for NF-B ligand (RANKL) and its receptors RANK and osteoprotegerin are key regulators of bone remodeling but also influence cellular functions of tumor and immune effector cells. In this work, we studied the involvement of RANK-RANKL interaction in NK cell-mediated immunosurveillance of acute myeloid leukemia (AML). Substantial levels of RANKL were found to be expressed on leukemia cells in 53 of 78 (68%) investigated patients. Signaling via RANKL into the leukemia cells stimulated their metabolic activity and induced the release of cytokines involved in AML pathophysiology. In addition, the immunomodulatory factors released by AML cells upon RANKL signaling impaired the anti-leukemia reactivity of NK cells and induced RANK expression, and NK cells of AML patients displayed significantly upregulated RANK expression compared with healthy controls. Treatment of AML cells with the clinically available RANKL Ab Denosumab resulted in enhanced NK cell anti-leukemia reactivity. This was due to both blockade of the release of NK-inhibitory factors by AML cells and prevention of RANK signaling into NK cells. The latter was found to directly impair NK anti-leukemia reactivity with a more pronounced effect on IFN- production compared with cytotoxicity. Together, our data unravel a previously unknown function of the RANK-RANKL molecule system in AML pathophysiology as well as NK cell function and suggest that neutralization of RANKL with therapeutic Abs may serve to reinforce NK cell reactivity in leukemia patients.
answer:
To the ligand of which receptors does Denosumab (Prolia) bind?


question:
There have been several milestones in the Paralympic movement. The first official Paralympic Games, no longer open solely to war veterans, was held in Rome in 1960 Summer Paralympics. 400 athletes from 23 countries competed at the 1960 Games. Since 1960, the Paralympic Games have taken place in the same year as the Olympic Games. The Games were initially open only to athletes in wheelchairs; at the 1976 Summer Paralympics, athletes with different disabilities were included for the first time at a Summer Paralympics. With the inclusion of more disability classifications the 1976 Summer Games expanded to 1,600 athletes from 40 countries. The 1988 Summer Paralympics in Seoul, South Korea, was another milestone for the Paralympic movement. It was in Seoul that the Paralympic Summer Games were held directly after the 1988 Summer Olympics, in the same host city, and using the same facilities. This set a precedent that was followed in 1992 Summer Paralympics, 1996 Summer Paralympics and 2000 Summer Paralympics. It was eventually formalized in an agreement between the International Paralympic Committee (IPC) and the International Olympic Committee (IOC) in 2001, and was extended through 2020. On March 10, 2018, the two committees further extended their contract to 2032. The 1992 Winter Paralympics were the first Winter Games to use the same facilities as the 1992 Winter Olympics.
answer:

Originally, participation in the Paralympic Games was limited to which group?