Transcription factor that binds to the E box motif 5'-CACGTG-3', probably in a heterodimeric complex with mxl-2 (PubMed:17826759). Involved in modulating longevity in response to TOR signaling, dietary restriction, the decline in protein homeostasis associated with normal aging, germline signaling and the insulin-like signaling pathway (PubMed:24699255, PubMed:27001890). Plays a role in autophagy (PubMed:27001890). Involved in regulating migration of the ray 1 precursor cells in the male tail, acting in concert with Wnt and semaphorin signaling pathways (PubMed:17826759). Regulates transcription of genes encoding extracellular matrix (ECM) components which may contribute to the substratum required for migration of the neighboring ray 1 precursor cells (PubMed:17826759). Involved in repressing infection by the microsporidian pathogen N.parisii, probably acting independently of its canonical partner, mxl-2 (PubMed:27402359). Nuclear localization is promoted by conditions of dietary restriction or reduced insulin-like/IGF-1 signaling in a pha-4-dependent manner. Expressed in intestine, neurons, muscle, hypodermis, excretory cell and other tissues. Expressed in epidermal cells as early as the 50-100 cell stage of embryogenesis and in intestinal cells at the 4E stage (PubMed:17826759). Expressed in non-migratory, syncytial epidermis at larval stage L1 (PubMed:17826759). RNAi-mediated knockdown reduces lifespan, which is further reduced on daf-2 or glp-1 mutant backgrounds (PubMed:24699255, PubMed:27001890). RNAi-mediated knockdown causes premature onset of polyglutamine-mediated paralysis (PubMed:24699255). RNAi-mediated knockdown increases spore levels of the microsporidian pathogen N.parisii during infection, on an mxl-2 or mdl-1 mutant background (PubMed:27402359).