SELP and neoplasm: To examine whether E- and P-selectin and tumour cell interactions took part in malignant progression in vivo, the transfected cells were injected subcutaneously in a total amount of 53 E- and P-selectin double knock-out scid mice (select), 19 of them with Fra-2 cl 1 cells, 18 with Fra-2 cl 2 cells, and 16 with control cells.