EMT, a critical step in metastasis and cancer development, requires the regulation of specific proteins by EMT-inducing transcription factors, such as TWIST1, SNAIL, SLUG, and ZEB proteins, so that phosphorylation, ubiquitination, acetylation, methylation, glycosylation, SUMOylation and other PTMs of these proteins induce activation/destabilization of EMT-inducing transcription factors and nuclear/cytoplasmic accumulation, promoting EMT or, on the contrary, mediating their ubiquitination and proteasomal degradation after their translocation in the cytoplasm. This evidence concerns the gene SNAI1 and cancer.