Figure 6b: GHK and GHK-PEG attenuated the viability of SH-SY5Y cells. The effect of GHK and GHK-PEG treatment on SH-SY5Y cell viability was assessed by plating cells in 96 well plates at 5000 cells per well and incubated for 24 hrs. Cells were either not treated or treated with GHK or GHK-PEG at 1 or 10 nM for 24 hrs. The effect of each treatment on cell viability was assessed by measuring protease activity using the cell permeant substrate GF-AFC using the ApoTox-Glo Triplex Assay. The results for each treatment were expressed as fold control and compared between nontreated and treated samples using analysis of variance (ANOVA). n=3; *p≤0.05.