We used FACS to sort live cells from dissociated P7 whole retina, VC1.1+ amacrine cells, and OFP+;Thy1.2− SACs cells, as described previously37,50. Amacrine cells were sorted by selection for monoclonal VC1.1 antibody (200 μg ml−1, Sigma) and an anti-IgM secondary conjugated to phycoerythrin-Cy7 (Southern) were applied to live suspension of dissociated retina cells. OFP+ SACs were sorted from OFP+ RGCs by negative selection of Thy1.2-PE-Cy7 labeled RGCs. In each condition, 2000 cells were sorted directly into RNA lysis buffer (Qiagen); RNA was purified and first strand cDNAs were generated with Superscript RT III (Invitrogen). Primers that uniquely detect the 22 Pcdhg variable exon-constant exon spliced transcripts were adapted from ref. 21, with modifications to avoid cross-hybridization. These primers, and others used to assess purity of the sorted population, are listed in Supplementary Table 1. PCR program used is: 94°C for 2 minutes; 30 cycles of 94°C for 20 seconds, 56°C for 30 seconds, 72°C for 1 minute; 72°C for 7 minutes.
