Complex sentence: Two more phosphates are added by other enzymes, and so after the attachment of the three phosphates gemcitabine is finally pharmacologically active as gemcitabine triphosphate (dFdCTP).
Split into simpler sentences: Two more phosphates are added by other enzymes. After the attachment of the three phosphates Gemcitabine is finally pharmacologically active as gemcitabine triphosphate (dFdCTP).