We have previously identified mitogen-activated protein kinase kinase 4 (MAP2K4; also known as MEK4, MKK4 or SEK1), a 399 amino acid protein, as a driver of metastatic transformation in human PCa, and as an important target of small molecule therapeutics designed to inhibit metastasis [3]. The gene discussed is MAPK4; the disease is posterior cortical atrophy.