ABCG2 and prostate cancer: Furthermore, luteolin showed promising effects upon prostate cancer stem cells through the down-regulation of matrix metaloproteinase-9 (MMP-9) (which is involved in self-renewal and angiogenesis) and the down-regulation of Sox-2 transcriptional factor (which is essential for stem cells pluripotency), ABCG2 efflux transporter, and the JNK signaling pathway [125].