PNMA2 and cancer: Lee et al. suggested that caffeic acid phenethyl ester (CAPE), a chemopreventive phytochemical derived from honeybee propolis, suppressed SK-Hep1 cell invasion in a dose-dependent manner by abolishment of matrix metalloproteinases (MM2 and MM9) which are associated with the invasive phenotypes of cancer cells and inhibition of NF-κB DNA-binding activity [35].