Primers 1–11 were used as forward primers in combination with primer no. 13 as the reverse primer to generate the indicated mutants. Primers 1 and 12 were used for generating CΔ150. The upstream and downstream primers have EcoRI and BamHI sites, respectively, for facilitating an in-frame cloning of the products into the EcoRI and BamHI sites of pCMV2-falg vector. In the primer sequences, italicized letters represent restriction sites for EcoRI and BamHI; bold letters represent gene-specific sequences.