Chlorotoxin is harmless to humans, but it binds to a type of cancerous brain cell and leaves regular cells alone.

氯毒素对人类无害，但它会与一种癌性脑细胞结合，而不会影响正常细胞。

So, gently touch the tip of a needle. You'll feel the metal, and those are your regular nerve cells.

所以，轻摸针尖。你可以感觉到金属，一般神经细胞会给你这种感觉。