KRT14 and breast cancer: A limited number of human breast cancer organoids exhibiting K14 expression were identified, with none of the K14-negative samples displaying invasive characteristics in collagen I. The K14-positive patient-derived breast cancer organoid (PDXO 1915)25, similar to the MMTV-PyMT organoids, invaded in 3D Collagen I as cohesive multicellular strands guided by K14 positive cells enriched with nuclear Yap (Fig. 3g).