The melanoma B16F10 cells proliferation inhibition may attribute to methoxy group at the C-5 or C-8 position for the chemical compounds bergapten and xanthotoxin, the mechanism behind the activity of these two compounds was due to G2/M arrest via an elevation of checkpoint 1 kinase (Chk1) phosphorylation and a plummet in the level of cdc2 phosphorylation [217]. The gene discussed is CHEK1; the disease is melanoma.