For the context within which they will be used, antibodies must be shown to be specific, selective, and reproducible. Antibodies should be chosen based on these criteria and be additionally validated with appropriate controls in the course of research. The resources below include information about antibody validation techniques, but also resources to identify antibodies previously validated for specific uses that may help in initial selection.
Validation of a cell line's species, sex, and tissue of origin are essential to ensuring that results can be interpreted correctly. This may be required at the time of submission to a journal, during peer-review or even after publication. Journals may already ask you to report the source and authentication status of cell lines. This could include reference to the first article describing the cell line. For example, information on what Nature is looking for can be found here.
First step (and simplest): check your cell line(s) against the list of known cross-contaminated or misidentified cell lines available on the NCBI Biosample home page (see below).
The NIH (and more frequently, journals as well) will want to know how you plan to authenticate your cell lines. Generally, STR testing and mycoplasma contamination testing are recommended. In both tests, the method used, the outcome, and the date last authenticated should be supplied. The materials linked to below contain more information on authentication best practices and standards.