CCN1 and cancer: In addition, several studies found that the activation of YAP increases the downstream gene expression of EGFR ligands such as amphiregulin (AREG) and neuregulin 1 (NRG-1), as well as connective tissue growth factor (CTGF) and cysteine-rich angiogenic inducer 61 (CYR61), forming an autocrine loop to reinforce the MAPK signaling pathway in order to induce drug resistance and cancer metastasis [75,76,94,95,96,97].