Thus, during the hypoxia simulated by means of CoCl2 in patient-derived tumor primary cultured cells, the expression of genes HIF-1α and AhR changed unidirectionally, whereas AhR and CYP1B1 expressions were activated by the inducer (B[a]P) only during the hypoxic state of the cultured tumor cells. Here, HIF1A is linked to neoplasm.