Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Input: Consider Input: Context: Cilostazol, a potent type 3 phosphodiesterase inhibitor, is found to reduce neointimal formation by inhibiting vascular smooth muscle cell (VSMC) proliferation. The aim of this study is to investigate whether the inhibitory effect of cilostazol on VSMC proliferation is operated via heme oxygenase-1 (HO-1).', 'In rat carotid arteries, cilostazol up-regulated HO-1 in the neointima of balloon-injured arteries. Treatment of human VSMCs with cilostazol enhanced the expression of HO-1, which was mainly regulated at the transcriptional level. Small interfering RNA knock-down of HO-1 attenuated the inhibitory effect of cilostazol on VSMC proliferation, suggesting the critical role of HO-1 in cilostazol effect. The transcriptional responsiveness of HO-1 to cilostazol was inversely correlated with the length of GT-repeat in human HO-1 promoter. Deletion and mutational analysis of HO-1 promoter along with chromatin immunoprecipitation showed that cyclic AMP response element (CRE)-binding protein (CREB) participated in cilostazol-induced HO-1 transcription. Furthermore, cilostazol triggered a linkage between the CRE and GT-repeat regions in the HO-1 promoter. The promoting effect of cilostazol on HO-1 expression, proliferation inhibition, and chromatin conformation in the HO-1 promoter was greater in VSMCs from subjects with shorter GT-repeat alleles than those with longer alleles.
Answer: Cilostazol inhibits VSMC proliferation involving an association between CREB and HO-1. The length polymorphism of GT-repeat in human HO-1 promoter determines the effect of cilostazol.

Output: Does gT-repeat length polymorphism in heme oxygenase-1 promoter determine the effect of cilostazol on vascular smooth muscle cells?


Input: Consider Input: Context: Pandemic strains of HIV-1 (group M) encode a total of nine structural (gag, pol, env), regulatory (rev, tat) and accessory (vif, vpr, vpu, nef) genes. However, some subtype A and C viruses exhibit an unusual gene arrangement in which the first exon of rev (rev1) and the vpu gene are placed in the same open reading frame. Although this rev1-vpu gene fusion is present in a considerable fraction of HIV-1 strains, its functional significance is unknown.', 'Examining infectious molecular clones (IMCs) of HIV-1 that encode the rev1-vpu polymorphism, we show that a fusion protein is expressed in infected cells. Due to the splicing pattern of viral mRNA, however, these same IMCs also express a regular Vpu protein, which is produced at much higher levels. To investigate the function of the fusion gene, we characterized isogenic IMC pairs differing only in their ability to express a Rev1-Vpu protein. Analysis in transfected HEK293T and infected CD4+ T cells showed that all of these viruses were equally active in known Vpu functions, such as down-modulation of CD4 or counteraction of tetherin. Furthermore, the polymorphism did not affect Vpu-mediated inhibition of NF-кB activation or Rev-dependent nuclear export of incompletely spliced viral mRNAs. There was also no evidence for enhanced replication of Rev1-Vpu expressing viruses in primary PBMCs or ex vivo infected human lymphoid tissues. Finally, the frequency of HIV-1 quasispecies members that encoded a rev1-vpu fusion gene did not change in HIV-1 infected individuals over time.
Answer: Expression of a rev1-vpu fusion gene does not affect regular Rev and Vpu functions or alter HIV-1 replication in primary target cells. Since there is no evidence for increased replication fitness of rev1-vpu encoding viruses, this polymorphism likely emerged in the context of other mutations within and/or outside the rev1-vpu intergenic region, and may have a neutral phenotype.

Output: Does a Naturally Occurring rev1-vpu Fusion Gene Confer a Fitness Advantage to HIV-1?


Input: Consider Input: Context: Progression from actinic keratosis (AK) to invasive squamous cell carcinoma (iSCC) of the skin is thought to occur after the development of full thickness epidermal neoplasia, as in the classic pathway of cervical cancer. Nevertheless, cutaneous iSCC may also directly arise from a proliferation of atypical basaloid cells limited mostly to the epidermal basal layer (AK I), akin to what happens in the 'differentiated pathway' of iSCC of the vulva, oral cavity and other locations.", 'To evaluate the prevalence of classic and differentiated pathways in the development of cutaneous iSCC.', 'The epidermis adjacent to and overlying iSCC, assumed to be representative of pre-existing lesions, was histologically studied in 196 skin biopsy specimens showing iSCC.', 'AK I, AK II and AK III lesions overlying iSCC were present in 63.8%, 17.9% and 18.4% of cases respectively. The corresponding percentages in the epidermis adjacent to iSCC were 77.9%, 6.6% and 8.3% respectively (stage could not be assessed in 8.1% of cases). Focal epidermal ulceration overlying iSCC was seen in 32% of AK I, 28.6% of AK II and 33.3% of AK III instances. Adnexal involvement by atypical keratinocytes (proliferative AK) was present more frequently in cases with overlying AK I (39/125, 31.2%) than with AK II (8/35, 22.9%) and AKII I (5/36, 13.9%).
Answer: Direct invasion from proliferating basaloid atypical keratinocytes limited to the epidermal basal layer (AK I), known as the differentiated pathway, was the most common form of progression to cutaneous iSCC in our series. On the other hand, stepwise progression from AK I to AK II and AK III (classic pathway) was seen to be operative in a substantial proportion of iSCC cases. All AK lesions, irrespective of intraepidermal neoplasia thickness, are therefore potentially invasive and tumour advance along adnexal structures might facilitate iSCC development from AK I lesions.


Output: Is actinic keratosis with atypical basal cells ( AK I ) the most common lesion associated with invasive squamous cell carcinoma of the skin?