I am working on a scientific paper and would like to ask a question regarding the use of "a role of" vs "roles of". "Dendritic cells play critical roles in expansion and antitumor efficacy of infused T cells" or "Dendritic cells play a critical role in expansion and antitumor efficacy of infused T cells" I wonder if I should use "critical roles of" because of "expansion and antitumor efficacy (plural)". Any comments would be appreciated. Thanks.
The question is not about grammar, it's about the number of roles that dentritic cells play.
If they play a single role - that is, perform a single function - stick to the singular role. It is not relevant whether this single function affects both expansion and anti-tumour efficacy.
If they play more than one, prefer the plural roles.
I would use a hyphen with T-cells