<P> Compared with chemotherapy or other anti-cancer drugs, there are a lot of advantages of siRNA drug . SiRNA acts on the post-translational stage of gene expression, so it doesn't modify or change DNA in a deleterious effect . SiRNA can also be used to produced a specific response in a certain type of way, such as by downgrading suppression of gene expression . In a single cancer cell, siRNA can cause dramatic suppression of gene expression with just several copies . This happens by silencing cancer - promoting genes with RNAi, as well as targeting an mRNA sequence . </P> <P> RNAi drugs treat cancer by silencing certain cancer promoting genes . This is done by complementing the cancer genes with the RNAi, such as keeping the mRNA sequences in accordance with the RNAi drug . Ideally, RNAi is should be injected and / or chemically modified so the RNAi can reach cancer cells more efficiently . RNAi uptake and regulation is monitored by the kidneys . </P> <P> The human immune system is divided into two separate branches: the innate immune system and the adaptive immune system . The innate immune system is the first defense against infection and responds to pathogens in a generic fashion . On the other hand, the adaptive immune system, a system that was evolved later than the innate, is composed mainly of highly specialized B and T cells that are trained to react to specific portions of pathogenic molecules . </P> <P> The challenge between old pathogens and new has helped create a system of guarded cells and particles that are called safe framework . This framework has given humans an army systems that search out and destroy invader particles, such as pathogens, microscopic organisms, parasites, and infections . The mammalian safe framework has developed to incorporate siRNA as a tool to indicate viral contamination, which has allowed siRNA is create an intense innate immune response . </P>

Explain how the process of rna interference works