However, since IgM is unable to bind FccRIIB, it fails to elicit negative feedback of humoral immunity. Thus, the imbalance of IgM and IgG in AID2/2 mice and humans could lead to unregulated B-cell proliferation, leading to the loss of peripheral tolerance. Other mechanisms, such as lack of high-affinity BIBW2992 antiidiotypic antibodies that might maintain B-cell homeostasis should also be considerable. Alternatively, insufficient elimination of external Ags due to the lack of class-switched and hypermutated Igs might drive B-cell activation. Elucidation of the precise mechanisms for unregulated B-cell proliferation as a result of AID deficiency is an important unresolved issue. Abiotic stresses, such as drought are primary factors that limit crop cultivation and yield worldwide. To cope with drought stress in rice , which consumes.70%of the water in agricultural areas �C resulting in the acceleration of the shortage of the limited fresh water �C recent research is applying integrated approaches including key genes that mediate plant responses to drought stress. For the characteristics that trigger global changes in drought-related genes, the application of transcription factor genes is becoming a powerful approach in the engineering of crop plants with enhanced tolerance to drought stress . Among the transcription factors, accumulating research shows that ethylene response factor proteins function in plant WZ4002 growth, development and processes in response to biotic and abiotic stresses . ERF proteins were identified as containing an ERF domainconserved motif that binds to GCC box, DRE and other cis-acting elements , acting as either a transcriptional activator or a repressor . For example, ERF activators CBF1/ DREB2A, DREB1A and OsDREB1F enhance tolerance to salt, drought and low temperature in both rice and Arabidopsis , whereas TSRF1 enhances pathogen resistance in tomato and tobacco . Most importantly, ERF proteins affect stress responses through modulation of a given metabolism or synthesis pathway. For instance, Sub1A is an ERF-like protein that confers tolerance to submergence and drought in rice through affecting ethylene synthesis . The rice ERF proteins SNORKEL1 and SNORKEL2 can trigger remarkable internode elongation via gibberellins to avoid submergence . Tomato JERF1 modulates the expression of an abscisic acid biosynthesis-related gene that enhances tolerance to drought, salinity and cold in tobacco . Moreover, investigations reveal that transcriptional repressors behave as negative regulators. For instance, ERF transcriptional repressors, AtERF4 and AtERF7 inhibit the expression of ethylene-responsive genes to decrease plant ethylene sensitivity through suppressing the expression of ABA-responsive genes .