Importantly, CA125 and HE4 are present in this quadrant, as well as other proteins that have been reported to be elevated in the sera of women with ovarian cancer, such as interleukin-6 [37–40], midkine [30–33], folate receptor-alpha [36], KLK6 [34], and hK11 [35]. Here, MDK is linked to ovarian carcinoma.