typecast

Reader's Digest 5月号の記事 Alzheimer's Is a bad diet to blame?の一部を抜粋します。
Until recently, insulin was typecast as a regulator of blood sugar, cueing muscle, liver and fat cells to extract sugar from the blood and use it for energy or store it as fat. We now know that the hormone is a master multitasker: in the brain, it helps neurons take up glucose for energy and regulates neurotransmitters crucial for memory and learning.
冒頭の文に出てきた単語、 "typecast"、を覚えたいので辞書を引きます。
・Dictionary.com:
1. to cast (a performer) in a role that requires characteristics of physique, manner, personality, etc., similar to those possessed by the performer.
2. to cast (a performer) repeatedly in a kind of role closely patterned after that of the actor's previous successes.
3. to stereotype: He realizes now he's been typecast as an executive errand boy.
なるほど、 "typecast" には役者にいつも同じ役割を当てることなのですか。確かにＴＶでも映画でも俳優によっては悪役とか、特定の性格の役割ばっかりの人がいますね。