FOS and cancer: Several proto-oncogenes involved in malignant transformation and cancer progression, including c-erbB1 family (HER1, ERBB1 or EGFR), c-myc, Fos and c-ras, are preferentially expressed by trophoblast cells during the first week of pregnancy when the proliferative, migratory and invasive properties of these cells are at their peak [2,3].