In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.

[EX Q]: Context: In our initial attempt to identify differentiation markers for ocular surface epithelia, we observed a unique staining pattern by a commercial anti-Galphaq antibody. We further isolate and characterize the protein reactive with this anti-Galphaq antibody in human ocular surface epithelia.', 'Human donor corneoscleral buttons were sectioned and stained with a battery of commercial antibodies against Galpha proteins. Western blot analysis of cell lysates of corneal epithelial cells and HEK 293 cells transfected with Galphaq cDNA was used to determine the identity of the protein reactive with the anti-Galphaq antibody (E-17). Comparisons were made with another anti-Galphaq antibody (G4415) and an anti-cytokeratin 12C (J7) antibody. The isolated proteins reactive with E17 and J7 were then analyzed with two dimensional isoelectric focusing. Polypeptide sequences were identified using matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) after in-gel protein digestion.', 'The E-17 anti-Galphaq antibody preferentially stained the entire corneal epithelia and the suprabasal layers of the limbus with complete absence of staining in the basal limbus and conjunctiva. Western blot analysis of corneal epithelial cells showed that E-17 antibody identified a protein with a molecular weight of 55 kDa. However, the antibody did not react with the purported antigen, Galphaq protein (42 kDa) produced by Galphaq cDNA. Another anti-Galphaq antibody (G4415) did not react with the 55 kDa protein but did react with the 42 kDa Galphaq protein. Further comparison of the E-17 antibody with the J7 antibody revealed that both recognized the 55 kDa band in one and two dimensional analysis. MALDI-TOF MS analysis confirmed that the 55 kDa protein of interest was actually cytokeratin 12 (CK12), rather than Galphaq protein.\Question: Is cytokeratin 12 in human ocular surface epithelia the antigen reactive with a commercial anti-Galpha q antibody?
[EX A]: The commercial E-17 anti-Galphaq antibody did not react with Galphaq protein, its purported antigen. Instead, it recognized a 55 kDa protein, which was characterized to be cytokeratin 12 by isoelectric focusing and peptide fingerprinting with mass spectrometry. Based on its reactivity with CK12, this commercial E-17 can be used as a differentiation marker to study ocular surface epithelia.

[EX Q]: Context: Reg IV, a secreted protein and member of the Reg multigene family, is up-regulated in malignancies of the human gastrointestinal tract, including colorectal carcinoma (CRC). However, in vitro signal transduction pathway(s) utilized by Reg IV are not yet known.', 'To determine the signaling pathway(s) responsive to Reg IV, we examined the effects of purified recombinant human Reg IV (rhR4) on HCT116 and HT29 colon adenocarcinoma cells.', 'Addition of rhR4 to cultures led to a dose-dependent increase in cell number similar to that observed after treatment with epidermal growth factor (EGF). In addition, rhR4 treatment resulted in rapid phosphorylation of EGF receptor at Tyr992 and Tyr1068 and Akt at Thr308 and Ser473. Using luciferase reporter gene assays, we demonstrated that Reg IV signaling through EGF receptor and Akt results in increased activator protein-1 (AP-1) transcription factor activity. Real-time reverse-transcription polymerase chain reaction and Western blot analyses revealed quantitative increases in c-Jun, JunB, JunD, and FosB expression associated with increased AP-1 activity. Electrophoretic mobility shift assay further revealed significant increases in AP-1 binding activity in rhR4-treated cells, with increased supershift in the presence of antibodies to JunB, JunD, and FosB. Furthermore, rhR4 treatments led to the increased expression of Bcl-2, Bcl-XL, survivin, and matrilysin, genes associated with a poor prognosis in advanced CRC.\Question: Does reg IV activate the epidermal growth factor receptor/Akt/AP-1 signaling pathway in colon adenocarcinomas?
[EX A]: Reg IV is a potent activator of the EGF receptor/Akt/AP-1 signaling pathway in CRC. Disruption of Reg signaling may have utility as a therapeutic intervention for human gastrointestinal adenocarcinomas.

[EX Q]: Context: Considering the hypothesis that androgen-independent but growth factor dependent epithelial cell division may be important in the development and progression of prostate cancer and that protein tyrosine kinases and phosphotyrosine protein phosphatases are key enzymes modulating the levels of specific phosphotyrosylated proteins implicated in several growth factor regulated signal transduction pathways, our aim was to study the cellular distribution of phosphotyrosine proteins in normal and hyperplastic dog prostates as well as in those of castrated dogs supplemented with either androgens or estrogens in order to modify the relative proportion of basal versus secretory epithelial cells.', 'Following the determination of optimal conditions to specifically detect phosphotyrosine proteins by a rabbit polyclonal antibody directed against phosphotyrosine, immunohistochemistry was performed on prostate tissue sections from these experimental animals. In addition to morphological criteria, an antibody to high molecular weight cytokeratins and antisera against arginine esterase were used to selectively identify basal and secretory cells. Since prostatic acid phosphatase may be involved in the local regulation of phosphotyrosine proteins, its distribution was also evaluated with a human prostatic acid phosphatase antiserum.', 'In all prostatic tissues examined, basal epithelial cells were preferentially and specifically stained with antiphosphotyrosine. The staining intensity per basal cell was highest in the estrogen-supplemented dogs. In addition, basal cells were numerically increased and all were highly immunoreactive for high molecular weight cytokeratins. In prostates displaying a well-differentiated glandular epithelium, the number of positive basal cells and their staining intensity varied in the following order: normal < hyperplastic < androgen-supplemented dogs. At all times, the levels of phosphotyrosine proteins in prostatic acid phosphatase and arginine esterase positive cells (secretory) remained low. Fibroblasts and smooth muscle cells were unreactive to antiphosphotyrosine, even though estrogen supplementation increased the prostatic stromal volume.\Question: Do phosphotyrosine antibodies preferentially react with basal epithelial cells in the dog prostate?
[EX A]:
The preferential localization of phosphotyrosine proteins in basal cells, their increased level per cell and the number of positive cells in the different experimental animals support the concept that basal cells represent the stem cells of the prostate. The sex steroid-mediated up-regulation of protein phosphorylation on tyrosine residues in these cells suggests that their proliferation is likely to involve growth factor regulated signal transduction pathways. In this respect, the lack of maturation of basal cells and the differentiation of secretory cells induced by androgen deprivation, combined with estrogen stimulation, favors the activation of these pathways and cell growth. On the other hand, the activation of glandular cell differentiation and the increase of stromal volume do not alter the threshold level of protein tyrosine kinase and phosphatase activities in secretory cells, fibroblasts and smooth muscle cells.