Leemor Joshua-Tor is a Howard Hughes Medical Institute investigator and professor at Cold Spring Harbor Laboratory (CSHL). She was trained at Tel-Aviv University, where she earned a bachelor’s degree in chemistry, and at the Weizmann Institute of Science in Rehovot, where she earned a doctorate in chemistry. She was a Jane Coffin Childs postdoctoral fellow at the California Institute of Technology prior to joining CSHL. At CSHL, she was the director of the undergraduate summer research program and then Dean of the School of Biological Sciences. Joshua-Tor is the recipient of the Dorothy Crowfoot Hodgkin Award from the Protein Society, a Beckman Young Investigator Award, the Mildred Cohn award, and is a fellow of the American Association for the Advancement of Science. She served on several advisory committees at the National Institutes of Health and is on the editorial boards of several international scientific journals. She is an elected member of the American Academy of Arts and Sciences and the National Academy of Sciences. Joshua-Tor’s laboratory studies the molecular basis of nucleic acid regulatory processes, in particular RNA interference (RNAi) and DNA replication. She is perhaps best known for her research revealing the inner workings of gene-silencing machinery components of RNAi. She discovered the role of a protein called Argonaute, also known as Slicer, at the heart of the RNAi machinery. In addition to basic mechanisms of gene silencing, she has been studying the regulation of the miRNA let-7, important in embryonic development and differentiation. She is also known for her studies of E1, a key factor in the replication of papillomavirus, a virus that causes cervical cancer. Joshua-Tor discovered how E1 moves along DNA, which has had implications for molecular motors in many fields of biology. More recently, she has been examining the eukaryotic DNA replication machinery with the human Origin Recognition Complex as the centerpiece of these studies.