RETNLB and infection: In the case of bacterial (e.g., Salmonella) infection, rapid differentiation and proliferation of secretory ECs such as Paneth cells (which secrete anti-microbial peptides, such as defensin and lysozyme) and goblet cells [which secrete mucin and anti-microbial proteins, such as TFF3 and resistin like β (RELMβ) (also known as FIZZ1)] is accelerated to clear the pathogens (23).