In other scenarios and in contrast to the therapy outlined above, recent research suggests that HIF induction in normoxia is likely to have serious consequences in disease settings with a chronic inflammatory component. It has also been shown that chronic inflammation is self-perpetuating and that it distorts the microenvironment as a result of aberrantly active transcription factors . As a consequence, alterations in growth factor, chemokine, cytokine, and ROS balance occur within the cellular milieu that in turn provide the axis of growth and survival needed for de novo development of cancer and metastasis. The results of a recently published study have numerous implications for a number of pathologies where NF-κB and HIF-1 are deregulated, including rheumatoid arthritis and cancer. Therefore, it is thought that understanding the cross-talk between these two key transcription factors, NF-κB and HIF, will greatly enhance the process of drug development. 
Nitric oxide may itself regulate NOS expression and activity. Specifically, NO has been shown to play an important negative feedback regulatory role on NOS3, and therefore vascular endothelial cell function [ citation needed ] . This process, known formally as S -nitrosation (and referred to by many in the field as S -nitrosylation), has been shown to reversibly inhibit NOS3 activity in vascular endothelial cells. This process may be important because it is regulated by cellular redox conditions and may thereby provide a mechanism for the association between "oxidative stress" and endothelial dysfunction. In addition to NOS3, both NOS1 and NOS2 have been found to be S -nitrosated, but the evidence for dynamic regulation of those NOS isoforms by this process is less complete [ citation needed ] . In addition, both NOS1 and NOS2 have been shown to form ferrous-nitrosyl complexes in their heme prosthetic groups that may act partially to self-inactivate these enzymes under certain conditions [ citation needed ] . The rate-limiting step for the production of nitric oxide may well be the availability of L -arginine in some cell types. This may be particularly important after the induction of NOS2.
DNA Fingerprinting: How is DNA evidence prepared and analyzed in a crime case? Students perform agarose gel electrophoresis to analyze DNA (dye simulation) samples from a mock crime scene. Based on DNA fingerprinting profiles with dyes simulated to represent the DNA a comparison is made to the crime scene, students determine which suspect likely committed the crime. This activity helps students understand how DNA variation in individuals can be analyzed in practical applications such as genetic testing and forensics. [50 minutes to introduce electrophoresis and practice pipetting, 50 minutes to run gels, partial next day to analyze results]