CST1 and cyst: To determine whether this defect was specific to GRA12 or was associated with other IVN-associated GRAs, we measured DBA fluorescence intensity at the cyst periphery of Δgra1, Δgra2, Δgra4, Δgra6, Δgra9, and Δgra12 cysts (Fig. 1D), which reflects wall cargo (DBA-stained CST1) delivered to the cyst wall, compared to the cyst interior, which reflects wall cargo not yet delivered to the cyst wall (Fig. S3).