UASt regulates expression of Spyo\Cas9 with a nuclear localization signal (NLS) at its N and C termini. An EGFP sequence is present downstream of Spyo\Cas9, separated by a T2A sequence - EGFP acts as a reporter for Spyo\Cas9 expression, while the presence of the self-cleaving peptide T2A sequence ensured that two independent proteins are made and that the EGFP tag does not hinder the activity of Spyo\Cas9.