The zymogens are released from the cytoplasm of tumor cells where they are inhibited by TIMPs.13,14 The excessive cleavage of the ECM associated with an imbalance of the MMPs/TIMPs ratio has been correlated with the invasive potential of brain tumor cells.7,43 We could observe by PCR that TIMP3 is highly expressed in cells overexpressing ATF3 but not following exposure to JS-K up to 3 μM. We conclude that the regulation of the inhibitors is not directly affected by NO and may need stronger promotor induction. This evidence concerns the gene ATF3 and brain neoplasm.