PTGER4 and breast cancer: We reported earlier that COX2/PGE2 induced VEGF-C/D production and tumor associated angiogenesis and lymphangiogenesis was inhibited by blocking EP4/PI3K/Akt signaling in breast cancer models (Xin et al., 2012; Majumder et al., 2014, 2018; Nandi et al., 2017).