KIT and posterior cortical atrophy: Moreover, PCa cells that overexpress CD117 and ATP-binding cassette super-family G member 2, ABCG2 (CD117+/ABCG2+), an ubiquitous ATP-binding cassette transmembrane protein that is highly expressed in multi-drug resistant tumor cells, are highly prolific and exhibit multidrug resistance, being able to self-renew and differentiate, as well as to generate tumors in vivo similar to the ones from which they were first isolated (Liu et al., 2010).