CFTR and cystic fibrosis: For example, the I655V mutation in the transmembrane α-helix of ERBB2 has been shown to increase risk of breast cancer and cystic fibrosis has been attributed to endoplasmic reticulum defects caused by misassembly of CFTR (the cystic fibrosis transmembrane conductance regulator) [37], making TMPs biological drug targets [38].