**2. Key components of the retinoic acid signaling pathway**

To understand how the RA signaling pathway is altered in cancer and to provide a basis for designing retinoid-based treatment approaches to cancer, we provide a brief description of the key components in the RA signaling pathway. The reader is referred to Das et al. [13] for more detailed information. Listed below are the main proteins essential to proper functioning of the RA signaling pathway. A simplified schematic of the RA signaling pathway is illustrated in **Figure 1**.
