Fig. 4: CAF co-implantation enables breast tumor formation in limited estrogen availability.

Quantification of the immunohistochemistry staining intensity for ER-α (A) of tissue sections from MCF7 tumors established without (B) or with (C) the support of CAF2 cells. Unpaired, two-sided Student’s t-test *P < 0.05. Tumor growth curves in mice either transplanted with MCF7 cells alone or in combination with CAF2 cells in the mammary fat pad with standard (0.5 mg) (D) or low (0.025 mg) (E) dose estrogen levels. The 60-day slow-release pellets were replenished as indicated below the x-axis. Tumor growth in the presence of an intermediate estrogen dose (0.1 mg) (F) was continually monitored without further estrogen supplementation. E2 = estrogen. Multiple unpaired, two-sided t-tests (Two-stage step-up (Benjamini, Krieger, and Yekutieli): ***P < 0.001, ****P < 0.0001. Error bars: SEM; n = 5 mice in each of the six groups.