CAMP and infection: Finally, as we found a significant synergistic effect of PBA on 25(OH)D3 induction on CAMP expression (Fig 5B), we investigated whether co-treatment with PBA enhanced 25(OH)D3-dependent restriction of Mtb growth via cathelicidin production over 7 days of culture, treating macrophages 4 hrs post-infection with either mono- or dual-therapy.