hCRBP expression differs widely among human breast cancer cell lines. A. RT-PCR Southern blot analysis of CRBP expression in ZR75-1, MTSV1-7, MCF-7 and MDA-MB-468 cells. B. RT-PCR Southern blot analysis of CRBP expression in MCF-7 subclones and again MDA-MB-468, to allow comparison with the cell lines studied in A. Cells were either untreated (MDA-MB-468) or treated with RA and TSA as further described in Fig. 4 (MCF-7 clone A and B cells). The data in Fig. 1 were used to generate Figs. 2A and 3A after densitometric analysis and normalization to autoradiographic exposure time (1 to 24 h) and GAPDH expression (loading control).