HEG1 and cancer: Heart development protein with EGF-like domain 1 (HEG1) was discovered during the study of a zebrafish heart [7] and is expressed in different tissues involved in various physiological processes such as angiogenesis [8,9], cell–cell junction [10], embryonic development [11,12], and cell proliferation [13] These processes are associated with tumor development and progression, suggesting that HEG1 may play a crucial role in cancer development.