Western blot (A) and densitometry (B) of total Ngf immunoprecipitated from the media collected from SOD1G93A and Ntg astrocyte co-cultured with non-transgenic motoneurons for 14 days. Western blotting showed the presence of two forms of Ngf: pro-NGF (33 kDa), and mutant Ngf (13 kDa). Densitometry revealed that in the medium from co-cultures of SOD1G93A astrocytes with non-transgenic motoneurons the pro-NGF/mutant Ngf ratio is 2-fold higher (P = 0.001, two-tailed t-test) than in co-cultures with non-transgenic astrocytes (n = 6; error bar = SD). (B) Densitometry results for pro-NGF/NGF ratio when co-cultures are treated with lactate, p75 inhibitor and fgfr1 inhibitor (n = 3; error bar = SD, one-way ANOVA). Statistical analysis was performed comparing all groups to Ntg (significance =*, where *= < 0.05; **=<0.01) or SOD1G93A (significance = #, where #= <0.05. n.s. = not significant) Levels of pro-NGF/NGF were also analysed for Ntg co-cultures, but there was no significant difference between treatments (data not shown).