MKI67 and neoplasm: A substantial increase in CAR T cell tumour infiltration into CXCL10- and CXCL11-expressing tumours, both in the presence and absence of an additional endothelial layer was confirmed in 12 h infiltration experiments, after relevant CAR T cell proliferation (measured by Ki-67 positivity) within 12 h post-co-culture initiation had been excluded as a confounder in a preliminary experiment (Fig. 5e, f, and Supplementary Fig. 19c).