Fig. 1: Experimental workflow schematic.

Barcode library is introduced into mammary carcinoma cell lines (EMT6 or 4T1) in vitro at a low multiplicity of infection (MOI). Cells are sorted based on red fluorescent protein (RFP) expression to select those having incorporated a barcode. Barcoded cells are then transplanted into the mammary fat pad of immunocompromised (NSG) or immunocompetent (WT) mice. Following immunoselection with either the endogenous immune system or immunotherapy, barcode abundance and diversity within the primary tumours and lung-bearing metastases are analysed. Source data are provided as a source data file.