### EPHB1 Gene Overview:
**Gene Symbol**: EPHB1  
**Location**: Chromosome 3 (exact location may vary in different organisms)  
**Function**: The EPHB1 gene encodes a receptor tyrosine kinase component of the Eph family. It plays a critical role in mediating cell-cell interactions, especially during developmental processes in the nervous system. It binds to ephrin-B ligands, activating bidirectional signaling pathways that influence cellular behaviors such as migration, differentiation, and adhesion. 

### Other Associated Genes:
While EFNB1, EFNB2, and EFNB3 are the primary functional ligands associated with EPHB1, other genes with potential connections include:
- **EPHA Family Members**: Like EPHA2 and EPHA5, which may have overlapping functional roles in neural development and stem cell biology.
- **SLIT2**: Involved in axon guidance and potentially interacts with the signaling pathways influenced by EPHB1.
- **RHOA**: This gene may have signaling pathways that are influenced by EPHB1 signaling, particularly in processes linked with cytoskeletal dynamics.

### Aging and Age-Related Diseases:
1. **Neurodegeneration**: EPHB1 has been implicated in processes critical for synaptic plasticity and neurodevelopment, suggesting potential roles in neurodegenerative diseases where synapse function is compromised.
2. **Muscle Aging**: EPHB1's role in regulating muscle stem cells suggests a potential involvement in sarcopenia and other age-associated muscle degenerative conditions.
3. **Tumorigenesis**: Alterations in EPHB1 and its signaling pathways have been studied in various cancers, potentially linking the gene's activity to mechanisms associated with aging and tumor progression.

### Drug Interactions:
There are currently no specific drugs that exclusively target EPHB1. However, several drug classes may interact with receptor tyrosine kinases, including:
- **Tyrosine Kinase Inhibitors (TKIs)**: Drugs that target receptor tyrosine kinases in cancer; indirect effects may impact EPHB1 signaling.
- **Monoclonal Antibodies**: Some monoclonal antibodies targeting other receptors in related pathways may influence EPHB1 activity.
- **Selective Modulators**: Drugs impacting ephrin signaling pathways broadly, though specific ones targeting EPHB1 require further elucidation.

### Pathways and Biological Processes:
EPHB1 is involved in various critical pathways:
1. **Ephrin Receptor Signaling Pathway**: Prominent in mediating cell adhesion and migration, crucial during development and tissue remodeling.
2. **MAPK/ERK Signaling Pathway**: Activated downstream of EPHB1, influencing cellular processes like proliferation and differentiation.
3. **Cell Communication**: Facilitates contact-dependent signaling mechanisms that are vital for neuronal development and synaptic function.
4. **Biological Processes**:
   - **Neuronal Development**: Critical for axon guidance and synaptic formation.
   - **Cell Proliferation and Migration**: Regulates cellular behaviors in developing tissues and during tissue repair.
   - **Dendritic Spine Maturation**: Impacts synaptic stability and plasticity.

### Summary:
Overall, EPHB1 is a multifunctional gene involved in pivotal biological processes and development, making it a significant focus for studying neural and muscle health, as well as age-related diseases. Its interactions with other genes, potential roles in aging, and relevance to drug development illustrate its importance in a broad range of biological and pathological contexts.