Mitosis includes four phases, prophase, metaphase, anaphase, and telophase. Like mitosis, meiosis also has distinct stages called prophase, metaphase, anaphase, and telophase. Progression from metaphase to anaphase is marked by sister chromatid separation. These stages are prophase, prometaphase, metaphase, anaphase, and telophase. Mitosis is composed of many stages which include, prophase, metaphase, anaphase, telophase, and cytokinesis, respectively. Both chromatids remain associated by cohesin complexes until anaphase, when chromosome segregation occurs. Micronuclei are structures formed by mitotic errors in the transition from metaphase to anaphase. Separase cleaves the cohesion molecules that hold the sister chromatids together to activate anaphase. Securin is a protein involved in control of the metaphase-anaphase transition and anaphase onset. The active, CDC20-bound APC (APC/C) targets mitotic cyclins for degradation starting in anaphase. In "nondisjunction", sister chromatids fail to separate during anaphase. It is required for two microtubule-dependent processes&colon; nuclear movement prior to anaphase, and chromosome separation. Genetic mosaicism can result from many different mechanisms including chromosome nondisjunction, anaphase lag, and endoreplication. Hair follicles in anaphase express four different caspases. This is known as a chromatin bridge or an anaphase bridge.