STRING 9.05 
NGF [ENSP00000358525]
nerve growth factor (beta polypeptide); Nerve growth factor is important for the development and maintenance of the sympathetic and sensory nervous systems. It stimulates division and differentiation of sympathetic and embryonic sensory neurons
NTF4 [ENSP00000301411]
neurotrophin 4; Target-derived survival factor for peripheral sensory sympathetic neurons
Evidence suggesting a functional link:
Neighborhood in the Genome:  
none / insignificant.
Gene Fusions:  
none / insignificant.
Cooccurence Across Genomes:  
none / insignificant.
none / insignificant.
Experimental/Biochemical Data:   yes (score 0.937).  
Association in Curated Databases:  
none / insignificant.
Co-Mentioned in PubMed Abstracts:   yes (score 0.860). In addition, putative homologs are mentioned together in other species (score 0.061).  
Combined Score:
Note: the two proteins have some sequence similarity (162.4 bits over 176 amino acids. click here to see the alignment).
Evidence for specific actions:
Binding:yes (score: 0.937)