<think>
Okay, I need to figure out how the pathway enrichment analysis was conducted in this article. Let me start by looking through the Methods section and other relevant parts.

First, the question is about the tool used for pathway enrichment. In the Methods under "DMRs and DMGs Identify," it says they used the DAVID web server. DAVID is a common tool for enrichment, so that's probably the answer for question 1.

Next, the version number of the tool. The text mentions DAVID but doesn't specify a version. The citation is to Huang da et al. 2009, which might correspond to DAVID 6.7 or 6.8, but since the paper was published in 2019, maybe a newer version, but since they didn't state it explicitly, the answer here is "not described."

For the gene set library, DAVID typically uses GO and KEGG. The Methods section explicitly states "GO and KEGG pathway of the DAVID web server," so both GO and KEGG were used. So question 3 is answered with those.

Regarding the background gene list, the authors mention that DMGs were analyzed with GO and KEGG via DAVID. DAVID usually uses all genes in the genome as background, but the paper doesn't specify if they defined a different one. Since they don't mention it, the answer is "not described."

Statistical test: DAVID uses a modified Fisher's exact test for enrichment. The Methods don't specify the test, but since DAVID's default is Fisher's, maybe that's implied. However, the authors might not have detailed it here. The answer might be "not described," but I need to check. The paper says "analyzed with GO and KEGG pathway of the DAVID web server" without details, so I'll go with "not described" unless there's more info. Wait, looking again, they might have used the tools within DAVID which typically use Fisher's exact test, but since it's not stated, the answer is "not described."

For false discovery rate (FDR), DAVID usually applies FDR correction (Benjamini-Hochberg), but the authors didn't mention whether they used it. The Methods section doesn't specify, so answer is "not described."

So summarizing:

1. Tool: DAVID web server
2. Version: Not described
3. Gene sets: GO and KEGG
4. Background: Not described
5. Statistical test: Not described
6. FDR correction: Not described
</think>

1. **Tool used for pathway enrichment analysis?**  
   DAVID web server  

2. **Tool version number provided?**  
   Not described  

3. **Gene set library queried?**  
   GO and KEGG  

4. **Background gene list defined?**  
   Not described  

5. **Statistical test used?**  
   Not described (implied to use DAVID's default, likely Fisher's exact test, but not explicitly stated)  

6. **False discovery rate (FDR) correction used?**  
   Not described (DAVID typically uses FDR, but not explicitly mentioned in the article)  

| **Aspect**                     | **Answer**                                                                 |
|-------------------------------|-----------------------------------------------------------------------------|
| Tool for pathway enrichment   | DAVID web server                                                           |
| Tool version number            | Not described                                                              |
| Gene set library               | GO and KEGG                                                                |
| Background gene list defined   | Not described                                                              |
| Statistical test               | Not described (likely Fisher's exact test via DAVID)                       |
| FDR correction used            | Not described (but DAVID may default to FDR; not explicitly stated)       |