FGFR1 and posterior cortical atrophy: We first performed preliminary analyses of potential novel circular RNAs derived from FGFR1 by RT-PCR and the FGFR1-derived circRNAs recorded in CircBase (http://www.circbase.org/) (Fig. 1A and Additional file 1: Fig. S1) that could be detected in PCa cells, which revealed 5 potential circRNAs expressed in PCa.