Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Example input: In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
Example output: In what year did francis, duke of anjou leave the netherlands?
Example explanation: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.
Q: The objective of this study was to analyze the expression levels of multiple components in the mammalian target of rapamycin (mTOR) signaling pathway in radical nephrectomy specimens from patients with metastatic renal-cell carcinoma (RCC) treated with mTOR inhibitors in order to identify factors predicting susceptibility to these agents. This study retrospectively included a total of 48 consecutive patients undergoing radical nephrectomy, who were diagnosed with metastatic RCC and subsequently treated with an mTOR inhibitor (everolimus or temsirolimus) as either first- or second-line systemic therapy. Expression levels of 5 molecular markers involved in the signaling pathway associated with mTOR, including PTEN, phosphorylated (p)-Akt, p-mTOR, p-p70 ribosomal S6 kinase, and p-4E-binding protein 1 (4E-BP1), were measured by immunohistochemical staining of primary RCC specimens. Of several factors examined, bone metastasis, liver metastasis, and the expression level of p-4E-BP1 were shown to have significant impacts on the response to the mTOR inhibitors. Progression-free survival (PFS) was significantly correlated with the expression levels of PTEN and p-4E-BP1 in addition to the presence of bone metastasis on univariate analysis. Of these significant factors, p-4E-BP1 expression and bone metastasis appeared to be independently associated with PFS on multivariate analysis. These findings suggest that it would be useful to consider the expression levels of potential molecular markers in the mTOR signaling pathway, particularly p-4E-BP1, as well as conventional clinical parameters when selecting patients with metastatic RCC who are likely to benefit from treatment with mTOR inhibitors.
A:
What does mTOR stands for?