In the present study, it was observed that fucoidan treatment could induce the apoptosis of PC-3 human prostate cancer cells via the activation of the ERK1/2 MAPK signaling pathway, the inactivation of p38 MAPK and PI3K/Akt, and inhibition of the Wnt/β-catenin signaling pathway. This evidence concerns the gene MAPK3 and prostate cancer.