With regard to MC, the low growth inhibition activity of MC-LR (GI50 > 5 μM at 24 h) in cancer cell lines [131] due to its low cell permeability in the absence of specific transporters, in conjunction with the moderate selectivity profile for PP1 and PP2A inhibition, has led the scientific community to overlook their therapeutic potential for years [132]. The gene discussed is PTPA; the disease is cancer.