The effect of the cocultureon PCa cell proliferation was assessedwith the cell cycle marker, CDKN1A, a broad-actingcyclin-dependent kinase inhibitor that encodes for the protein p21,whose expression anticorrelates with PCa growth in vitro and in vivo(51−53) (Figure 2D). The gene discussed is CDKN1A; the disease is posterior cortical atrophy.