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: It is unanimously accepted that there is an unmet need for pain medications that are both effective and safe. Unfortunately, no really novel analgesics have been approved over the past three decades. In view of both experimental and clinical evidence of a major role for nerve growth factor (NGF) in the generation and maintenance of a wide range of pain states, drug discovery efforts focusing on the development of anti-NGF agents have aroused particular interest. Several humanized anti-NGF monoclonal antibodies (mAbs) have entered clinical trials as potential analgesics. In this respect, tanezumab is at an advanced stage of clinical development while fulranumab, fasinumab and ABT-110, previously known as PG110, are in early phases of clinical development. This Current Opinion article aims at describing the rationale for targeting NGF for pain, reviewing the analgesic efficacy and safety of anti-NGF agents based on data from fully published studies, conference abstracts, and the US Food and Drug Administration (FDA) website, and discussing the possible future of these agents in managing chronic pain. Anti-NGF mAbs produced significant pain relief and functional improvement in patients with osteoarthritis of the knee and/or hip. Conversely, studies in non-specific lower back pain generated mixed results; overall, this condition appeared to be less responsive to anti-NGF agents than osteoarthritis. Finally, there was no conclusive evidence of the effectiveness of anti-NGF mAbs in some types of chronic visceral or neuropathic pain. Furthermore, these studies raised safety concerns about anti-NGF mAbs. As a class, these drugs may cause or worsen peripheral neuropathies. But the most problematic issue-which prompted the FDA to place studies of these compounds on clinical hold in 2010-was rapid joint destruction leading to joint replacement surgery. The aetiologies of these side effects have been much debated and their pathophysiology is poorly understood. After an Arthritis Advisory Committee meeting held in March 2012, pharmaceutical companies negotiated with the FDA on the conditions for restarting clinical studies. Although the FDA lifted its clinical hold, there remain many unresolved issues about the long-term efficacy and safety of anti-NGF mAbs. While acknowledging that the future of these drugs is unforeseeable, it appears that they may not be the safe and effective painkillers that have been awaited for decades. 
 Question: What is the target of tanezumab?
ngf

Context: We show that overexpression of Polo-like kinase 4 (Plk4) in human cells induces centrosome amplification through the simultaneous generation of multiple procentrioles adjoining each parental centriole. This provided an opportunity for dissecting centriole assembly and characterizing assembly intermediates. Critical components were identified and ordered into an assembly pathway through siRNA and localized through immunoelectron microscopy. Plk4, hSas-6, CPAP, Cep135, gamma-tubulin, and CP110 were required at different stages of procentriole formation and in association with different centriolar structures. Remarkably, hSas-6 associated only transiently with nascent procentrioles, whereas Cep135 and CPAP formed a core structure within the proximal lumen of both parental and nascent centrioles. Finally, CP110 was recruited early and then associated with the growing distal tips, indicating that centrioles elongate through insertion of alpha-/beta-tubulin underneath a CP110 cap. Collectively, these data afford a comprehensive view of the assembly pathway underlying centriole biogenesis in human cells. 
 Question: Where in the cell do we find the protein Cep135?
centrosome

Context: Ginger Pye is a book by Eleanor Estes about a dog named Ginger Pye. 
 Question: What person illustrated Ginger Pye?

eleanor estes

