YAP1 and neoplasm: However, when PP1A is suppressed or Par3 overexpression possibly results in its mislocalization and/or over-activation in tumor cell lines, Par3 may bind to LATS1 and YAP without PP1A interaction, by which Par3 functions as a tumor suppressor to promote YAP phosphorylation and target gene repression, even YAP’s degradation.