ACTR2 and gastric carcinoma: While CpG island methylation in the promoter of human Arp2/3 complex subunit p41-Arc (ARPC1A) was found in only 1 of 22 gastric carcinomas in the 2002 study [25], all 32 primary cancer samples examined for the 2004 study showed decreased expression of one or more Arp2/3 subunits.