ATM and keratoconus: PCR analysis of RNA extracted from 3 KC cell lines, 3 KCATMΔ+ cell lines and 4 KCATMΔΔ cell lines showed that all KC lines expressed the Atm wildtype transcript, all KCATMΔΔ lines expressed the deleted (floxed) Atm transcript, and all KCATMΔ+ cell lines expressed both the wildtype and deleted Atm transcript (Supplementary Figure 2).