To test the hypothesis that LPA signaling promotes the expansion of BCSCs via PKD-1, we examined the expression of PKD-1 in a syngeneic BC model in mice with high-fat diet (HFD)-induced obesity that generates excessive LPA22 and in mice on a normal diet with or without the administration of LPA. Here, PKD1 is linked to obesity due to melanocortin 4 receptor deficiency.