Fig. 2: Reciprocal expression of ID2 and TFCP2L1 in human BC cells.

a–c ID2 and TFCP2L1 transcript (a) and protein (b, c) levels in basal (5637 and HT1197), luminal (HT1376), and mixed (T24 and UMUC3) subtypes of muscle-invasive BC (MIBC) as well as in RT4 non-muscle-invasive BC cells. b Western blot analysis of ID2, TFCP2L1, and CDK1 in the indicated human BC cell lines. β-Actin was used as the loading control. Molecular weight (MW) marker sizes (in kD) are shown on the left. c Representative images of double immunofluorescence staining of ID2 (green) and TFCP2L1 (red) proteins at 200× magnification are shown. Scale bars = 100 µm. Nuclei were stained with DAPI (blue). d ChIP–qPCR assay of Flag-TFCP2L1 binding to the promoter region of ID2 in basal HT1197 and luminal HT1376 muscle-invasive BC (MIBC) cells (n = 4). A schematic diagram of the ID2 locus and the sites recognized by primers used in the ChIP–qPCR assay are shown in the top panel. Quantitative data are expressed as the mean ± SEM values. Statistical analyses were performed using two-way ANOVA with the Bonferroni post hoc test. *p < 0.05, ***p < 0.001 compared with the Flag control group. e Protein expression of ID2 and TFCP2L1 in the indicated BC cells 4 days after infection with lentiviruses expressing the TFCP2L1 ORF or shRNA specific for TFCP2L1 (shTFCP2L1). The exact P-values and numbers of biological replicates can be found in the source data.