MEDICAL SCIENCES. For the article “WNT/β-catenin mediates radiation resistance of mouse mammary progenitor cells,” by Wendy A. Woodward, Mercy S. Chen, Fariba Behbod, Maria P. Alfaro, Thomas A. Buchholz, and Jeffrey M. Rosen, which appeared in issue 2, January 9, 2007, of Proc Natl Acad Sci USA (104:618–623; first published January 3, 2007; 10.1073/pnas.0606599104), the authors note that in Fig. 1D Right, the x-axis labels were transposed. The corrected figure and its legend appear below.
Fig. 1.
Clinically relevant doses of radiation increased the percentage of progenitor cells (%SP and Sca1+) in primary MEC culture and human MCF-7 cells. (A) MECs were isolated from BALB/c mice, cultured for 3 days, irradiated, and analyzed for %SP by Hoechst 33342 staining and flow cytometry. Radiation selectively increased the progenitor fraction (%SP) (P = 0.015 for 2 Gy, 0.008 for 4 Gy, and 0.05 for 6 Gy by the two-tailed t test). (B) MCF-7 cells were analyzed for %SP by Hoechst 33342 staining and flow cytometry. Radiation selectively increased the progenitor fraction (%SP) (P = 0.05 for 0 Gy vs. 4 Gy by the two-tailed t test). (C) Cells were analyzed for Sca1 in the SP 24 h after irradiation. Radiation selectively increased the Sca1+ (progenitor) fraction within the SP by killing the more sensitive Sca1− (nonprogenitor) cells (P < 0.05 for Sca1+ to Sca1− at 0 Gy vs. 2–8 Gy). The differences in effects of doses of 2 Gy vs. higher doses were not significant. (D) Anesthetized BALB/c mice were immobilized supine, and mammary glands (entire ventral surface) were irradiated. MECs were isolated 48 h after irradiation and analyzed immediately for Sca1 by flow cytometry. Radiation selectively increased the Sca1+ (progenitor) fraction and decreased the Sca1− (nonprogenitor) cells. ∗, P < 0.0001.