Intermediate filaments.

It is likely that future studies involving a molecular biology approach, similar to those described in [7,27,28], will yield fruitful information regarding properties and cellular roles of IF. At this point, our knowledge of the properties and expression of IF remains in stark contrast to our lack of understanding of their biological functions. As pointed out by Franke et al. [29], several lines of investigation have suggested that IF do not serve a general cellular function (i.e. 'housekeeping duties'). Instead, the roles of IF and their constituent proteins are probably related to specific functions of the differentiated cell. Our search for these specific roles will be difficult, but exciting. In the meantime, it is rewarding that IF typing of cells and tumors has already yielded practical information useful in histology and cytology [30].