PPARD and breast cancer: FABP5 expression is positively regulated via EGFR/ERK/phophatidylinositol-3-kinase signaling and activation of the transcription factor NF-kappaB, which is pro-tumorigenic in breast cancer, while Krüppel-like factor KLF2 inhibits FABP5 expression, reducing PPARβ/δ activity, and consequently, is tumor-suppressive [297].