First Person is a series of interviews with the first authors of a selection of papers published in Journal of Cell Science, helping early-career researchers promote themselves alongside their papers. Karolina Losenkova is first author on ‘Compartmentalization of adenosine metabolism in cancer cells and its modulation during acute hypoxia’, published in JCS. Karolina is a PhD student in the lab of Gennady Yegutkin at Medicity Research Laboratory, University of Turku, Finland, investigating the role of purine-converting enzymes in tumorigenesis.