NF-κB plays a pivotal role in immunity and inflammation and is considered to be a promising candidate for drug development. However, global suppression of NF-κB may have undesirable side-effects. Our data and the results of others suggest that each of the five NF-κB subunits may have a specific function in controlling the expression of inflammatory mediators in immune cells. Identifying the role for each NF-κB subunit in primary human immune cells will allow a more targeted approach to inhibiting NF-κB subunit-specific cellular functions. However, results obtained with primary human cells can often be inconsistent due to donor heterogeneity. Therefore one possible approach could be to generate human immune cell lines with stably inhibited expression of specific NF-κB subunit(s) as described in this chapter.