GCaMP6s is a genetically encoded fluorescent Ca[2+] indicator that shows high sensitivity and slow decay kinetics. It consists of the calmodulin-binding peptide M13, a circularly permuted green fluorescent protein and calmodulin. GCaMP6s contains the following mutations relative to GCaMP5G : K78H, T381R, S383T and R392G (FBrf0235079). For detailed kinetic and spectral properties and a comparison of GCaMP6s with other GCaMP series sensors, see FBrf0235079.