. (a) Mammary fat-pad reconstitution assay of NMuMG-GFP and E1KD-GFP cells orthotopically implanted into the cleared fat-pad of 3-week old female NOD/SCID mice. (b) Quantification of tumor volume over time in female NOD/SCID mice injected with E1KD shSCR, shILEI, and shLIFR cells at concentrations of 1k, 10k, and 100k cells per injection into the mammary fat-pad region (error bars represent mean +/− SEM n≥4; ****p<0.0001, 2-way ANOVA; shSCR is significant compared to shILEI and shLIFR in 100k cell injections, shSCR is significant compared to shILEI in 10k cell injections). (c) Final mammary tumor weight quantification from female NOD/SCID mice injected with 1k, 10k, and 100k E1KD shSCR, shILEI, and shLIFR cells into the mammary fat-pad region with a TIC frequency displayed for each condition (error bars represent mean +/− SEM, n≥4, ***p=0.0002, One-way Anova; E1KD shSCR 100k condition is significant when compared to the shSCR 10k and 1k conditions, as well as all shILEI and shLIFR conditions). (d) H&E staining of metastatic area in lungs of female NOD/SCID mice injected with E1KD shSCR, shILEI, and shLIFR cells into the mammary fat-pad. Representative images show lungs with the largest metastatic burden for each cell condition. Metastatic area percentage is shown for these images. (e) Immunoblot analysis of LIFR in NMuMG, E1KD, and E1KD cells injected into NOD/SCID fat pads and cultured from mouse primary tumor formation (M1P) and lung metastases (L1P).