The following information accompanied stocks donated to the Bloomington Stock Center by Richa Rikhy and Jennifer Lippincott-Schwartz, NIH. P{UASp-RFP.KDEL} was constructed by fusing the bovine preprolactin signal sequence with RFP followed by the KDEL endoplasmic reticulum retention signal. The tagged protein is diffusible within the ER. P{UASp-RFP.KDEL}8 is a second chromosome insertion. P{UASp-RFP.KDEL}10 is a third chromosome insertion.