ID1 and cancer: Importantly, there are many EMT-TF families, such as Snail (zinc finger proteins Snail and Slug), Zeb (zinc finger and homeodomain proteins Zeb1 and Zeb2), and Twist (basic helix-loop-helix proteins E12, E47, Twist1, Twist2, and Id), which have important functions in the normal development of human and EMT processes associated with cancer biology.