Together, our results revealed that loss of PRLR expression in HR + MCF7 cells resulted in loss of cell-cell junctional complexes and a shift from luminal to basal-stem like cellular plasticity and that blocking YAP-CCN2 signaling with the chemical inhibitor VPF reestablished proper intercellular junctional adherence and luminal differentiation phenotype in breast cancer cells deficient in PRLR expression. Here, YAP1 is linked to breast cancer.