CA9 and squamous cell carcinoma: First evidence for a bicarbonate transport metabolon in cancer cells was provided by the laboratory of Silvia Pastorekova and Jaromir Pastorek in hypoxic squamous cell carcinoma and lung carcinoma cells.72,175 The authors demonstrated that CAIX accumulates in the lamellipodia of hypoxic A549 lung carcinoma cells, where it colocalised with the Na+/HCO3− cotransporter NBCe1.72,175 CAIX also colocalised with the Cl–/HCO3– exchanger AE2 in the leading edge of SiHa squamous cell carcinoma cells, which migrated from hypoxic spheroids.