Increased CCR4 expression in active systemic lupus erythematosus.

A receptacle connector assembly (1) comprises an insulative housing (18) with a number of contacts (31, 41) retained therein and a pair of keying devices (50). The housing defines a first large-dimensioned receiving cavity (11) and a second small-dimensioned receiving cavity (21). The first receiving cavity has a channel (17). Each keying device comprises an engaging portion (511; 521) received in the first receiving cavity for being pushed outward by the mating plug connector, a resilient portion (513; 523) extending from the engaging portion, and a tongue (512; 522) extending from the resilient portion and projecting into the channel.