Gain- and loss-of-function genetic screens are important approaches to conduct such studies. ShRNA knockdown, ectopic gene expression and CRISPR technologies are techniques to carry out loss- and gain-of-function experiments for biomedical research. ShRNA, Open Reading Frame (ORF) and CRISPR libraries have been demonstrated to be powerful tools of genetic screens: shRNA, CRISPR knockout or interference libraries enable large-scale loss-of-function screens while ORF or CRISPR activation libraries allow large-scale gain-of-function screens. In the field of cancer research, these screens have been widely used for identifying oncogenes, tumor suppressors, metastasis regulators, drug resistance genes and new therapeutic targets. The Functional Genomics Core (FGC, previously the CCSG shRNA and ORFeome Developing Shared Resource consolidated with the institutionally supported Gene Editing and Cellular Model Core) was established to distribute shRNA and cDNA clones with reduced costs for The University of Texas MD Anderson Cancer Center laboratories, to provide shRNA, ORF and CRISPR libraries to CCSG cancer center members and to continue to develop other CRISPR-related technologies.