The mRNA levels for proteins associated with basal lamina assembly, cytoskeleton, WNT7B and CTHRC1 were down‐regulated, whereas the expression of CA1 mRNA was up‐regulated in the tumour cell lines treated with the anti‐CA I autoantibody positive sera.22 To examine the effect of the opposite phenomenon, the CA1 mRNA of PC3 prostatic cancer cells was directly targeted and silenced using the RNA interference system. This evidence concerns the gene CA1 and prostate cancer.