The transcriptional activity of full-length activated Ci/GLI proteins is restricted by their rapid ubiquitin-mediated degradation after initiation of Hh signaling (Ohlmeyer et al, 1998; Humke et al, 2010; Tukachinsky et al, 2010; Wen et al, 2010). Ubiquitination of Ci, GLI2 and GLI3 is mediated by the E3 ligase complex SPOP:CUL3:RBX1, which ubiquitinates the transcription factors in a Hh-dependent manner (Zhang et al, 2006; Kent et al, 2006; Zhang et al, 2009; Chen et al, 2009).
