Yes, EFFECTORS is a Scrabble word!

Letter values in Scrabble US: E 1, F 4, F 4, E 1, C 3, T 1, O 1, R 1, S 1.

Is it a valid word?

EFFECTORS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

one who brings about a result or event; one who accomplishes a purpose
a nerve fiber that terminates on a muscle or gland and stimulates contraction or secretion
an organ (a gland or muscle) that becomes active in response to nerve impulses