28901
Through a series of in vitro studies , the essential steps for intracellular drug delivery of paclitaxel using a pH - responsive nanoparticle system have been investigated in breast cancer cells .
 Chemical: paclitaxel
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: paclitaxel