Detection of WF after the purification of ascitic fluid from Walker tumour-bearing rats. A – pure ascitic fluid (As) and purified WF were loaded (10 μg protein) in 12% SDS-polyacrylamide gel followed by 1% Amido Black staining. B – samples of pure ascitic fluid (As) and purified WF were resolved by SDS-PAGE on 12% gels followed by Western blotting; the WF expression were analysed by probing 0.45 mm enhanced chemical luminescence (ECL) nylon membranes with biotinylated anti-PIF antibody (diluted 1:150) followed by detection with the secondary antibody streptavidin horse radish HRP-labelled (dilution 1:1000). Images of the stained and Western blot gels were captured (FTI 500 Image Master VDS, Pharmacia Biotech). Legend: As – pure ascitic fluid, WF – Walker factor obtained by purification and concentration of ascitic fluid, M – marker (220 to 14 kDa).