Fig. 3

Low levels of CD24 are sufficient to maintain tumorigenicity properties. a Quantitative RT-PCR analysis of CD24 mRNA in cells infected with control or CD24 shRNA as indicated. b Fluorescence-activated cell sorting analysis of CD24 expression in cells transfected with control or CD24 shRNA. c 1*10³ CD24⁺/control and CD24⁺/CD24-KD cells were seeded and grown in full medium for 3 days; the relative proliferation rate between the cells was determined using the Cyquant proliferation assay. d Representative photomicrographs of a tumorspheres (>50 um diameter) grown from CD24⁺/control and CD24⁺/CD24-KD single cells in non-adherent culture for 5 days (upper panel). Percentage tumorsphere formation efficiency (TFE %) comparison between CD24⁻ and CD24⁺ (lower panel). e Cells were injected into the fourth mammary fat pad of 8-week-old virgin wild-type mice. Tumor volume was measured at necropsy. The Mann-Whitney test was performed to compare CD24⁺/control and CD24⁺/CD24-KD cells (*p <0.05)