In order to assess the effect of reduced activity of Csk on the protein levels of individual members of SFKs, we performed Western blotting of two types of cancer cells (HCT116 and HeLa S3 cells) transfected with small interfering RNA (siRNA) for Csk (siCsk_1, SASI_Hs02_00328637, and siCsk_2, SASI_Hs02_00328637) or control siRNA. The gene discussed is CSK; the disease is cancer.