Difficult to treat cancer patients, specifically those tumors that are metastatic and drug-resistant, prove to have the lowest survival rates when compared to more localized types. The commonplace combination therapies, surgery, chemotherapy, and radiation, do not usually result in remission and sometimes cannot be done with these specific patients. RNA interference therapeutics, especially those that use short-interfering RNA (siRNA), have given rise to a novel field that employs the mechanisms in the body to silence the gene expression post-transcriptionally. The main cell types used in this research were Ewing Sarcoma, Acute Myelogenous Leukemia, and Rhabdomyosarcoma cells. Initial assays involved the testing of the cells' responsiveness to a panel of siRNA compounds, to better understand the most effective ones. The siRNA UBBs1 proved to be the most cytotoxic to all cell lines tested, allowing for further investigation through transfection procedures for cellular assays and RNA purification for expression analysis. The data showed decreased cell viability for the UBBs1 treated group for both RD and RH-30 Rhabdomyosarcoma cell lines, especially at a much lower concentration than traditional chemotherapy drug dose response assays. The RNA purification and quantification of the transfected cells over time showed the biggest decrease in gene expression when treated with UBBs1. The use of siRNA in future therapeutics could be a highly-specific method to induce cytotoxicity of cancer cells, but more successful clinical testing and better manufacturing processes need to be established first.