ERBB2 and breast cancer: Using the MDA-MB-231 human breast cancer cell line model, Cho et al. demonstrated that phosphorylation of the MARCKS ED induced the activation of the proto-oncogene receptor protein tyrosine kinase (PTK) ErbB-2 (also known as HER2) by binding to antiproliferative protein Transducer of ERBB2, 2 (TOB2) that regulates cell cycle by inhibiting progression from the G0/G1 to S phases [77].