SLX4 was immunoprecipitated from 1 mg of the following cell extracts: wildtype MEFs, SLX4 null MEFs or SLX4 null MEFs complemented with wildtype SLX4, using 1 ug of anti-SLX4 (1266-end mouse) S819C antibody. The immunoprecipitates were subjected to SDS-Page, before being immunoblotted with 0.5 ug/ml of anti-SLX1 (mouse) S778C antibody.