Figure 3: GHK and GHK-PEG inhibit U937 cell proliferation. The effects of GHK and GHK-PEG on malignant cell proliferation was first tested on U937 cells which were plated in 24 well plates and treated with GHK or PEGylated GHK at 10 and 20 nM for 24 hours and cell proliferation was assessed using a hemocytometer and the effect of each treatment was compared between control and treated samples using analysis of variance (ANOVA). n=6; *p≤0.05.