Several studies have investigated individually the role of uPAR, CD44 and MDR1 in various malignancies [5], [13], [14], [17], [19], 24,27,28,29,30,31,32, however, to our knowledge this is the first study that provides evidence for expression of CD44 and MDR1 on uPAR-positive cells in SCLC. This evidence concerns the gene ABCB1 and small cell lung carcinoma.