FIGURE 6.

Stable and transient knockdown of gC1qR decreases RTK activation. Control (sh-con and sh-con) and stably and transiently gC1qR-depleted (sh-gC1qR #1 and si-gC1qR) A549 cells were serum-starved for 18 h and then stimulated with insulin (100 nm), IGF (20 ng/ml), EGF (50 ng/ml), or serum (10%) for 15 min. The expression of gC1qR, Akt, phospho-Akt (p-Akt on Ser-473), Erk, and phospho-Erk (p-Erk) was determined by immunoblotting. Tyrosine phosphorylation of IRβ, IGFR, and EGFR was determined by immunoprecipitation following immunoblotting with an anti-phosphotyrosine antibody.