and contrastly, overexpression of NF-YA has resulted in drought resistance. NF-YB subunit The NF-YB family is, similar to the NF-YA subunit, variable in length, however, on average much smaller than the NF-YA subunit (90–240 amino acids in "M. truncatula"). They have been characterized with a structure and amino acid composition similar to the histone fold motif (HFM). This is composed of three alpha-helices separated by two beta strand-loop domains. Similar to NF-YA, NF-YB has been shown to also improve drought resistance when overexpressed and also the promotion of flowering in Arabidopsis. NF-YC subunit The NF-YC proteins are an intermediate size between that of NF-YA and NF-YB proteins (117–292 amino acids in M. truncatula) and also contain the HFM that is prevalent in NF-YB proteins. It has also been shown to be involved in flowering time in certain plants (overexpression leads to earlier flowering) where its influence is potentially regulated by the binding of the protein CONSTANS (CO) to the NF-YC subunit. NF-Y complexes Because of the evolutionary change in NF-Y encoding genes in plants, they subsequently have a large range of potential trimeric complexes. For example, in Arabidopsis, 36 NF-Y transcription factor subunits (including 10 NF-YA, 13 NF-YB, and 13 NF-YC subunits) have been identified and which could theoretically form 1690 unique complexes (which contains one of each type of subunit). This number, of course is higher than what actually happens since some subunits have specific binding patterns. Functional analyses on NF-Y encoding genes in plants have shown, as a result of their evolutionary diversification relative to their animal counterparts, have acquired diverse specific functions, such as embryo development, flowering time control, ER-stress, drought stress, and nodule and root development. This may only be a small portion of their capabilities, since the number of theoretically combinations of NF-Y complexes is so large and only a small portion can actually be created (less than 10% of all possible interactions were confirmed in both directions in yeast). CCAAT enhancer binding proteins (C/EBPs) Another aspect of the CCAAT binding motif is the CCAAT/enhancer binding proteins (C/EBPs). They are a group of transcription factors of 6 members (α-ζ), which are highly conserved and bind to the CCAAT motif. While research on these binding proteins is relatively recent, their function has been shown to have vital roles in cellular proliferation and differentiation, metabolism, inflammation, and immunity in various cells, but specifically hepatocytes, adipocytes, and hematopoietic