16851
Moreover , specific changes in the target bring resistance to specific drugs like modification in nucleotide synthesis enzymes upon anti - metabolite exposure , in microtubule composition upon spindle poison treatment , in topoisomerase activity upon topoisomerase inhibitor incubation or in intracellular signaling pathways when targeting tyrosine kinase receptors .
 Chemical: nucleotide; Chemical: tyrosine
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: nucleotide; Chemical: tyrosine