Figure 4: GHK inhibits SH-SY5Y cell proliferation. To test the effects of GHK and GHK-PEG on SH-SY5Yneuroblastomacell proliferation, cells were plated in 24 well plates and treated with GHK or PEGylated GHK at 10 and 20 nM for 24 hours and the effect of each treatment on cell proliferation was assessed using a hemocytometer. The effect of each treatment was compared between control and treated samples using analysis of variance (ANOVA). n=6; *p≤0.05.