Extended Data Figure 6. Biclonal configuration of tumors reconstituted from sorted iWnt/mRFP⁺ tumor cell subsets.

a, Sorted tumor cell subsets inefficiently reconstitute tumors. Three independent iWnt/mRFP⁺ bi-clonal tumors were resolved into component basal and luminal tumor cell subsets by FACS. Each tumor harbored a different basally-restricted HRas mutation, as indicated. 10⁵ sorted tumor cells were injected orthotopically into intact, post-pubertal mammary glands of wild-type host mice maintained on chronic Dox treatment. *Shown as number of reconstituted tumor outgrowths per injected gland. b, Tumor cells from a parental iWnt/mRFP⁺ tumor harboring a basally-restricted HRas^GGA12GAA mutation were resolved into basal and luminal cell subsets by FACS. When these isolated tumor cell subsets were injected orthotopically into the mammary glands of Dox-treated wild-type hosts, few tumors were reconstituted. However, tumors that did arise always were comprised of basal HRas^mut/Wnt1^low and luminal HRas^wt/Wnt1^high subsets, implicating interclonal cooperation in tumor reconstitution (n = 3 tumors reconstituted from the basal cell-enriched subset; n = 4 tumors reconstituted from the luminal cell-enriched subset).