Survival factor
Survival factors are drugs or biologically-occurring proteins that promote the health of nerve cells, such as photoreceptors. There are many different types of survival factors. Examples include, ciliary neurotrophic factor (CNTF), pigment epithelium-derived factor (PEDF), basic fibroblast growth factor (bFGF) and glial-derived neurotrophic factor (GDNF).
see IGF-1