The **GPN2** gene (GTPase, nuclear 2) encodes a small GTPase that plays a crucial role in the localization of RNA polymerases II and III, which are essential for the transcription of most protein-coding genes and the synthesis of various non-coding RNAs, respectively. Below, I provide additional information related to your specific requests:

### 1. Associated Genes
While specific gene associations with GPN2 may not be directly cited in comprehensive datasets, small GTPases often interact with a range of other proteins and play roles in various signaling pathways. Some related genes/proteins that involve small GTPases or are implicated in similar processes include:
- **RHOA**, which is involved in cytoskeletal dynamics.
- **RAC1**, involved in actin cytoskeletal reorganization.
- **Cdc42**, which plays roles in cell signaling and cytoskeletal regulation.
- **GAPDH**, which can interact indirectly through metabolic pathways related to nucleic acid synthesis.

### 2. Aging or Age-Related Diseases
Currently, specific research directly linking GPN2 to aging or age-related diseases is limited. However, GTPases are involved in various cellular processes that can affect aging, such as:
- **Cellular stress response**: Proper function of RNA polymerases is crucial for the expression of genes involved in stress responses, which can have implications in cellular aging.
- **Cancer**: Alterations in transcriptional regulation by small GTPases like GPN2 may contribute to oncogenesis, particularly as cancer prevalence increases with age.

### 3. Drug Interactions
While specific drugs targeting GPN2 have not been widely reported, drugs or drug classes that modulate GTPase activity or target the signaling pathways involving such proteins may indirectly affect GPN2 functions, including:
- **Antitumor agents**: Compounds that target pathways involving RNA synthesis or GTPase functions in oncogenic processes.
- **Immunosuppressants**: These may impact GTPases involved in cellular signaling.

### 4. Pathways and Biological Processes
GPN2 is involved in several critical biological processes, including:
- **Transcription regulation**: Crucial for the assembly and localization of RNA polymerase II and III, directly affecting mRNA and non-coding RNA synthesis.
- **RNA polymerase assembly**: GPN2 is required for RNAP assembly, which is a precursor to nuclear import.
- **Cellular processes related to proliferation**: As GTPases are involved in pathways relevant to cell division and growth, GPN2's functions can have broader implications in cell cycle regulation.

### Summary
The GPN2 gene serves as an important component of the cellular machinery that governs transcription, particularly in relation to RNA polymerases II and III. Although direct associations with aging or specific drugs are not as thoroughly documented, its role in cellular regulation suggests it could be impacted by pharmacological agents or pathways related to age-related cellular dysfunction and cancer progression. Further investigation into GPN2 could potentially uncover more details about its associations with other genes, aging processes, and drug interactions.