PKD1 and breast cancer: The role of PKD1 in promoting breast cancer stemness is further corroborated by Jiang Y and collaborators, who demonstrate that in estrogen receptor-positive breast cancer lysophosphatidic acid (LPA) induces PKD1 activation, which, in turn, stimulates the MAPK-ERK1/2 signaling pathway, thus resulting in the transcription of stemness-associated genes, including Notch1, ALDH1, CD36, CD44 and KLF4 [96].