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.

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?
ibrutinib

Context: Mahjong, that favorite pastime of "old folks" in Shanghai, is finding a new audience among younger players, and many university students are becoming mad about this traditional Chinese game. Students at Fudan University have even formed a Mahjong club. This resurgence of the game, however, is not without its critics. Some people still associate the game with gambling and for many years Mahjong was banned in China. One critic, surnamed Meng, was quoted as saying, "Mahjong is a bad custom that will distract students from studies." But Yu Guangyuan, former vice-president of the Chinese Academy of Social Sciences , says Mahjong is a "healthy, scientific, friendly mind game." Mr. Yu's opinion seems to be shared by the majority of Chinese. They see the game as an activity that requires great concentration and intellectual skill. They also see the game as an important part of Chinese culture and a pastime that brings family and friends closer together. This Spring Festival many families will no doubt spend hours around the Mahjong table getting reacquainted with each other. For them, playing Mahjong is a way of spending quality family time. No one knows who invented Mahjong. Some say it was Confucius, others say the current form of the game was developed right here in Shanghai in the late19th century. It is certainly because of Shanghai that the game enjoys its worldwide popularity. It was brought to America in the 1920s and has since spread throughout Europe and other parts of Asia. There is now a World Championship of Mahjong which is held every year. This year's championship was held in Chongqing and attracted players from America, Europe and Russia, as well as students from Peking University, Tshinghua University and Nankai University. There was no prize money, but the players delighted in using their wits and their understanding of statistics and probability theory to defeat their clever opponents. Of course, Mahjong doesn't have to always be that intense. For young people it can be a way to relax and to socialize, a chance to get away from their computers and talk to other people face to face. So, this Spring Festival, why not get out the "old folks" tiles: it's good to be mad about Mahjong! 
 Question: What is the best title of the passage?
mad about mahjong

Context: 1. In order to investigate the biological function of the human CLN3 gene that is defective in Batten disease, we created a yeast strain by PCR-targeted disruption of the yeast gene (YHC3), which is a homologue of the human CLN3 gene. 2. The phenotypic characterization revealed that the yhc3 delta mutants are more sensitive to combined heat and alkaline stress than the wild-type strains as determined by inhibition of cell proliferation. 3. This suggests that the yhc3 delta mutant is a good model to investigate the biological function of human CLN3 gene in mammalian cells and to understand the pathophysiology of juvenile Batten disease. 
 Question: What is the effect of a defective CLN3 gene?

jncl