Involvement of the PI3K/Akt in suppression of breast cancer migration/invasion. Activation of the PI3K/Akt pathway is the causative mechanism for the suppression of breast cancer migration/invasion induced by GM3S silencing. (a) Upper panels: the expression and activation of Akt detected by immunoblotting with anti-Akt, anti-p-Akt Ser (473), and anti-p-Akt Thr (308) antibodies. Lower panels: quantitation of these blots after normalization with the GAPDH blot. (b) Upper panels: PI3K inhibitor LY294002 restored the phosphorylation of Akt in 4T1-siGM3S2 cells. Lower panels: the quantitation of the blots after normalization with the GAPDH blot. (c) The migration and invasion abilities of GM3S-silenced 4T1 cells were enhanced by LY294002. *P < 0.05, **P < 0.01. CMP, cytidine 5'-monophosphate; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; GM3S, CMP-N-acetylneuraminic acid:lactosylceramide 2,3-sialyltransferase; PI3K, phosphoinositide-3 kinase.