KIRREL1 and neoplasm: KIRREL1 knockout led to the activation of YAP.107,108 Recently, integrated screens revealed KIRREL as a cell surface tumour suppressor involved in the Hippo pathway that could bind directly to SAV1 to activate this pathway.109 In addition, it was shown that the palmitoylation of TEAD was also regulated by cell density.110 Reportedly, other cell density transmitters for the Hippo pathway include E-cadherin,111 annexin A2,112 and the polarity-regulating kinase PAR1b.113