Supplementary Figure 1: Definition of retinoid resistance by morphology, and TALE family gene expression response to RA. A) Prototypical RA-sensitive and RA-resistant NB cell lines, treated with DMSO and 13-cisRA. The cell lines LAN-6 and CHLA90 are RA-sensitive cell lines, with smaller cell bodies and some neurite formation in complete media under control conditions (DMSO); when treated with 13-cisRA, proliferation slows and long neuritic processes develop extending from the cell bodies. In contrast, the RA-resistant cells CHLA15 and SK-N-AS have flatter and larger cell bodies under control conditions and no neurite formation or significant apoptosis when treated with 13-cisRA. B) Expression of TALE gene family members other than PBX1 do not correlate with treatment with 13-cisRA. The relative mRNA expression of PBX2, PBX3, PBX4 (top row), MEIS1, MEIS2, MEIS3 (middle row), and PKNOX1 and PKNOX2 in 4 RA-resistant cell lines (blue bars) and 11 RA-sensitive cell lines (red bars), as measured by RT-qPCR.