PIK3CA and neoplasm: Moreover, somatic mutations of the components involved in the activation of the PI3K pathway include mainly PIK3CA encoding the PI3K catalytic subunit p110α, PIK3R1 encoding the PI3K regulatory subunit p85α, and other genes encoding PI3K-related regulators, and it has been reported that PIK3R1 encodes p85a, followed by the action of downstream MMPs to play a tumor suppressor role [13–16].