NRG1 and cancer: Heregulin expression levels varies among those cancers, and patients with higher heregulin-expressing cancer cells were shown to exhibit more refractory and shorter progression free-survival with EGFR-TKIs such as erlotinib in NSCLC and with anti-EGFR antibodies such as cetuximab in CRC compared to patients with lower heregulin expression [23, 25, 26].