Fig. 1: p97 expression is higher in the breast CSC population.

a Representative immunohistochemical staining of p97 in human breast, colon, liver, and pancreatic cancers and adjacent noncancerous tissues. Bar: 20 μm. b Representative immunohistochemical staining of high-level p97 (red) co-stained with CD44 (brown, left) and CD24 (brown, right) in two consecutive serial sections of human breast cancer tissues. c Representative immunohistochemical staining of low-level p97 (red) co-stained with CD44 (brown, left) and CD24 (brown, right) in two consecutive serial sections of human breast cancer tissues. Bar: upper 200 μm, lower 50 μm. Note that p97 primarily localized to CD44⁺/CD24⁻ cells but not other cells. d Percentages of p97 expression in CD44⁺/CD24⁻ cells and non-CD44⁺/CD24⁻ (CD44⁻/CD24⁻, CD44⁻/CD24⁺, and CD44⁺/CD24⁺) cells in breast cancer tissues (n = 75). e Immunohistochemical staining of SOX2 and p97 in the consecutive serial sections of breast cancer tissues. SOX2 and p97 expressions were classified as low and high. Bar: upper 200 μm, lower 50 μm. f Correlation analyses of SOX2 and p97 expression in breast cancer tissues (n = 75). g Immunoblotting of p97 in lysates of MCF10A, MCF-7, and MDA-MB-231 cells. GAPDH was used as a loading control. h Left: flow cytometry analysis of CD44 and CD24 in MCF10A, MCF-7, and MDA-MB-231 cells. Right: the CD44⁺/CD24⁻ percentages. i qPCR analysis of P97 mRNA in CD44⁺/CD24⁻, non-CD44⁺/CD24⁻, ALDH⁺, ALDH⁻, PKH26⁺, and PKH26⁻ populations. j, k Immunoblotting analysis of p97, OCT4, and SOX2 in CD44⁺/CD24⁻, CD44⁻/CD24⁻, ALDH⁺, and ALDH⁻ populations isolated from MCF-7 and MDA-MB-231 cells. GAPDH was used as a loading control. Data were shown as mean + SD. *P < 0.05 and ***P < 0.001.