The biochemical and morphological evidence of an increase of nuclear HIF-1α – detected in our SMC cultures of IPEC-J2 cells – is an important indication of the exposition of the cells to oxidative stress, comparable to the oxygen deficit as it occurs in tumours.27 Furthermore, the morphological detection of HIF-1α in the histology of the cell cultures may serve as prognostic factor in the clinical progress of different tumours such as lung, breast and bladder cancer. The gene discussed is HIF1A; the disease is urinary bladder carcinoma.