CEACAM3 and infection: Activation of PKD1, critical for the uptake of PorBIA-expressing gonococci, is not involved in invasion of Opa-expressing bacteria via CEACAM-receptors on Chang cells (Fig. S6A,B) and inhibition of PI3K activity did not prevent invasion via CEACAM3 [42], [43], indicating the usage of alternative infection routes by these phase-variable bacteria.