Forced expression of a handful of transcription factors (TFs) can induce conversions between cell identities； however, the extent to which TFs can alter cell identity has not been systematically assessed. Here, we assembled a “human TFome,” a comprehensive expression library of 1,578 human TF clones with full coverage of the major TF families. By systematically screening the human TFome, we identified many individual TFs that induce loss of human-induced-pluripotent-stem-cell (hiPSC) identity, suggesting a pervasive ability for TFs to alter cell identity. Using large-scale computational cell type classification trained on thousands of tissue expression profiles, we identified cell types generated by these TFs with high efficiency and speed, without additional selections or mechanical perturbations. TF expression in adult human tissues only correlated with some of the cell lineage generated, suggesting more complexity than observation studies can explain.
