To investigate whether the knockdown of uPAS components and associated signalling proteins impairs the tumour progression of BT549 and MDA-MB-231 cells in vitro, uPAR, uPA and IGF1R were transiently downregulated, also in combination, in BT549 cells using several targeting and control small interfering RNAs (siRNAs, Additional file 2: Figure S1a and Additional file 3: Figure S2a). Here, IGF1R is linked to neoplasm.