Although this entire developmental process is multifactorial and requires additional mutations, epigenetic alterations associated with changes in the expression in tumor suppressors (e.g., Trp53, Cdkn2a) and EMT-related transcription factors, primary and metastatic tumor cells with mesenchymal characteristics were dependent on the persistent expression of oncogenic RAS for tumor cell growth and survival in vivo. This evidence concerns the gene TP53 and neoplasm.