PCDH1 and breast cancer: In human breast cancer cells, transient siRNA-mediated knockdown of all three GRHL orthologs show a reduced chromatin accessibility on GRHL-regulated enhancer elements that encode proteins required for cell-cell adhesion such as protocadherin-1 (PCDH1) and serine peptidase inhibitor 1 (SPINT1) (Jacobs et al., 2018).