the fbxl3 protein has also been found to cooperatively degrade c-myc when bound to cry2. the c-myc protein is a transcription factor important in regulating cell proliferation. the cry2 protein can function as a co-factor for the fbxl3 ligase complex and interacts with phosphorylated c-myc. this interaction promotes the ubiquitination and degradation of the c-myc protein.