These are molecules that exist naturally in cell membranes and are activated by certain enzymes and kinases generated by receptors.

这些分子存在于细胞膜表面,能被受体激活的某种酶或激酶所活化

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So, it doesn't need to bind to a receptor on the surface of the cell in order to work because the molecule can actually enter the cell directly.

所以无需与细胞表面受体相结合来起效,因为这些分子能直接进入细胞

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