Quantification of calreticulin redistribution in LNCaP prostate cancer cells using a fixed-cell imaging workflow.

Calreticulin (CRT) is an endoplasmic reticulum chaperone that can localize to the cell surface under stress, where it functions as a damage-associated molecular pattern. Quantifying surface-exposed CRT in prostate cancer models is challenging due to low baseline expression and variability in imaging workflows. We describe a fixed-cell immunofluorescence method to distinguish intracellular and surface CRT in LNCaP cells. Cells treated with thapsigargin exhibited increased surface localization. We introduce a redistribution factor (RF = ectoCRT/(ectoCRT + endoCRT)) to quantify CRT partitioning. This approach provides a reproducible framework for assessing CRT redistribution using standard fluorescence microscopy.