In this directed case study, students analyze data, draw a research-based conclusion, interpret experimental results, and discuss the relevance of research findings for clinical practice. Specifically, students examine the effects of chemotherapeutic drugs on newly generated cell lines and explain research outcomes using their prior knowledge of signal transduction pathways (G-protein coupled receptors), hormones, glycolysis, oxidative phosphorylation, and DNA structure and function as they follow the story of "Emily," an undergraduate student who is accepted into an internship program focusing on the breast cancer cell line MCF-7. Emily learns that MCF-7 cells can survive the treatment of tamoxifen and a hormone deprivation regimen, which leads to the generation of new cell lines (Tam3 and TamR3) that do not activate the mTOR signaling pathway. Emily attempts to predict how the Tam3 and TamR3 cells will respond to the mTOR inhibitor rapamycin, and then incorporates drugs used for chemotherapy into her experiments. Originally written for upper-level undergraduate biology majors, the case study is also appropriate for courses focusing on cell biology, pharmacology, and cancer biology.