Transcriptional cofactor (PubMed:21862562). Heterochronic protein, involved in timing of a subset of differentiation events during the larval-to-adult transition (PubMed:21862562). Promotes hypodermal terminal differentiation, together with transcription factor lin-29, perhaps as part of a transcriptional complex (PubMed:21862562). Involved in regulating molting by repressing the expression of nuclear hormone receptors nhr-23 and nhr-25 in the adult hypoderm, probably acting in concert with lin-29 (PubMed:21862562). Interacts with transcription factor lin-29 (via C-terminus). Expressed in pharyngeal cells throughout development, vulval precursor cells during the larval L3 stage, and the seam cells and hypodermal syncytia derived from the seam cell lineages throughout the larval L4 stage and adulthood. Belongs to the NAB family.