It isn't illegal to chew gum, but it is illegal to bring them into Singapore or sell them except for medical purposes. Since you can't buy gum (selling is illegal) there's no way to chew them so it's almost as good as not being able to chew gum. See this: http://www.customs.gov.sg/leftNa...
Definition: In Vitro. A study done in vitro, in contrast, looks at how a drug or procedure responds in the confines of a test tube or laboratory dish. Clinical trials or medical studies may be performed either in vivo or in vitro.
An in vitro application is the use of these rapidly selectable. noncytopathic RNA vectors for cell culture studies. After. efficient RNA transfection by electroporation, puromycin. selection is imposed, and a population of cells expressing the. gene of interest is derived in a matter of days.