Figure 4: Crabp1-dependent induction of apoptosis by compounds 3 and 4.

(A) Images showing apoptosis of Crabp1-positive MOVCAR cells (pSIVA staining, green). Cells were treated with 100 nM for 24 hrs. Quantitation of pSIVA positive cells shown on the right: *p < 0.001 versus control, n = 3, EV: empty vector. (B) Decrease in Bcl-2 protein by atRA, compound 3 or 4 (left), without altering mRNA expression (right). (C) Increase in cleaved caspase 3 (upper right), which is blocked by ERK1/2 inhibitor (below) in MOVCAR. This is abolished in the absence of Crabp1 (upper left, EV) under 100 nM RA, C3, and C4 treatment for 24 hrs. Quantification of cleaved caspase 3 is shown (upper, n = 4). (D) Compounds lose ability to induce ERK activity in human CRABP1 null cancer cell lines A2780 (ovarian) and KPC (pancreatic ductal carcinoma) after 100 nM, 30 min treatment (upper). Compounds are able to induce apoptosis after 24 hr treatment (lower) in CRABP1 positive MCF7 breast cancer cell line (lower right). Quantification of cleaved caspase 3 is shown for MCF-7. Data (A–D) are representative of at least 3 independent experiments.