Reports suggest that β-hCG can inhibit apoptosis3 or stimulate the growth of cancer cells and that elevated serum levels of β-hCG correlate with increased aggressiveness of the cancer.4, 5 Further, it has been shown that β-hCG promotes the invasion of prostate cancer cells by activating ERK1/2 and MMP-2, as well as decreasing the expression of E-cadherin in prostate cancer cells thus leading to poor disease prognosis.6, 7, 8 Interestingly, anti β-hCG vaccines have been developed and found to be active against β-hCG expressing cancer cells in vitro. Here, MAPK3 is linked to prostate cancer.