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U-box containing ubiquitin E3 ligase proteins play key roles in the regulation of diverse developmental processes such as cell death, defense responses, and flowering in monocots and dicots. We have previously demonstrated that SPOTTED LEAF 11 (SPL11), a rice U-box E3 ubiquitin ligase, is essential for the fine tuning of programmed cell death (PCD) and flowering in rice. Loss of function spl11 gamma-ray mutant showed lesion mimics, enhanced resistance to two different rice pathogens and delayed flowering under the long day conditions (Zeng et al., 2004; Vega-Sanchez et al., 2008). To elucidate the molecular and biochemical mechanisms by which SPL11 controls PCD and/or flowering time, yeast two-hybrid (Y2H) screens were performed using SPL11 as the bait, and eight proteins were identified as putative SPL11 interactors (SPINs). Among them, SPIN1, a signal transduction and activation of RNA (STAR), interacts with SPL11 in the nucleus and represses flowering via transcriptional perturbation of heading date 3a (Hd3a), an ortholog of FLOWERING LOCUS T (FT) in Arabidopsis (Vega-Sanchez et al., 2008). Interestingly, another RNA-binding protein, RNA binding interactor of SPIN1 (RBS1), was identified through additional Y2H screens using SPIN1 as the bait. Transient expressions of RBS1 in rice protoplasts and leaves of Nicotiana benthamiana showed abrupt host cell death in both systems. In addition, over-expression of RBS1 in rice resulted in lesion mimicry and dwarfism in T1 generation. These results suggest that SPL11 might regulate program cell death through SPIN1/RBS1 protein complex.